diff --git a/LICENSE b/LICENSE
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+++ b/LICENSE
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+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
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+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
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+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    {one line to give the program's name and a brief idea of what it does.}
+    Copyright (C) {year}  {name of author}
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    {project}  Copyright (C) {year}  {fullname}
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/app/Main.hs b/app/Main.hs
new file mode 100644
--- /dev/null
+++ b/app/Main.hs
@@ -0,0 +1,231 @@
+{- cluster-tree
+Gregory W. Schwartz
+
+Hierarchical spectral clustering of data.
+-}
+
+{-# LANGUAGE BangPatterns      #-}
+{-# LANGUAGE DataKinds         #-}
+{-# LANGUAGE DeriveGeneric     #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeOperators     #-}
+{-# LANGUAGE StandaloneDeriving #-}
+
+module Main where
+
+-- Standard
+import Data.Maybe (fromMaybe, catMaybes)
+import GHC.Generics
+
+-- Cabal
+import Data.Char (ord)
+import Data.List (intercalate)
+import Data.Monoid ((<>))
+import Options.Generic
+import Safe (atMay)
+import System.IO (stdin)
+import Text.Read (readMaybe)
+import TextShow (showt)
+import qualified Control.Lens as L
+import qualified Data.Aeson as A
+import qualified Data.Aeson.Encode.Pretty as A
+import qualified Data.ByteString.Lazy.Char8 as B
+import qualified Data.Csv as CSV
+import qualified Data.Map.Strict as Map
+import qualified Data.Set as Set
+import qualified Data.Text as T
+import qualified Data.Vector as V
+import qualified Numeric.LinearAlgebra as H
+import qualified System.FilePath as File
+import Math.Graph.Types
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Load
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Graph.Components
+import qualified Math.Clustering.Hierarchical.Spectral.Dense as HD
+import qualified Math.Clustering.Hierarchical.Spectral.Eigen.AdjacencyMatrix as HS
+
+newtype Delimiter  = Delimiter { unDelimiter :: Char } deriving (Read, Show)
+newtype Row        = Row { unRow :: Int } deriving (Eq, Ord, Read, Show)
+newtype Column     = Column { unColumn :: Int } deriving (Eq, Ord, Read, Show)
+newtype OutputTree = OutputTree { unOutputTree :: String } deriving (Read, Show)
+newtype MinSize    = MinSize { unMinSize :: Int } deriving (Read, Show)
+newtype NumEigen   = NumEigen { unNumEigen :: Int } deriving (Read, Show)
+
+data ClusteringType = Sparse | Dense deriving (Read, Show)
+data Components a = Single (ClusteringTree a) | Multiple [ClusteringTree a]
+
+instance A.ToJSON Q where
+      toEncoding = A.genericToEncoding A.defaultOptions
+instance A.FromJSON Q
+
+instance (A.ToJSON a) => A.ToJSON (ClusteringVertex a) where
+      toEncoding = A.genericToEncoding A.defaultOptions
+instance (A.FromJSON a) => A.FromJSON (ClusteringVertex a)
+
+-- | Command line arguments
+data Options = Options { clusteringType :: Maybe String
+                                       <?> "([Sparse] | Dense) Method for clustering data."
+                       , delimiter      :: Maybe Char
+                                       <?> "([,] | CHAR) The delimiter of the CSV file. Format is row,column,value with no header."
+                       , minSize        :: Maybe Int
+                                       <?> "([Nothing] | INT) Minimum size of a cluster."
+                       , numEigen       :: Maybe Int
+                                       <?> "([1] | INT) Number of eigenvectors to use while clustering with kmeans. Takes from the first eigenvector. Recommended to start at 2 and work up from there if needed."
+                       , minModularity  :: Maybe Double
+                                       <?> "([0] | DOUBLE) Minimum modularity to be over to continue recursion."
+                       , eigenGroup     :: Maybe String
+                                       <?> "([SignGroup] | KMeansGroup) Whether to group the eigenvector using the sign or kmeans while clustering. While the default is sign, kmeans may be more accurate (but starting points are arbitrary)."
+                       , separateComponents :: Bool
+                                           <?> "Whether to first separate connected components of the graph first. Will output a dendrogram for each component with the name of the tree and the number of nodes within the tree, along with the base set by --output-tree."
+                       , outputTree     :: Maybe String
+                                       <?> "([Nothing] | FILE) The name of the file to output the tree in JSON format."
+                       }
+               deriving (Generic)
+
+modifiers :: Modifiers
+modifiers = lispCaseModifiers { shortNameModifier = short }
+  where
+    short "minSize" = Just 'S'
+    short x         = firstLetter x
+
+instance ParseRecord Options where
+    parseRecord = parseRecordWithModifiers modifiers
+
+main :: IO ()
+main = do
+    opts <- getRecord "cluster-tree, Gregory W. Schwartz.\
+                      \ Hierarchical spectral clustering of data Computes real\
+                      \ symmetric part of matrix, so ensure the input is real\
+                      \ and symmetric. Diagonal should be 0s for\
+                      \ adjacency matrix.\
+                      \ Format is row,column,value with no header.\
+                      \ Must end with a newline."
+
+    let readOrErr err       = fromMaybe (error err) . readMaybe
+        clusteringType'     =
+          maybe Sparse (readOrErr "Cannot read --clustering-type")
+            . unHelpful
+            . clusteringType
+            $ opts
+        delim'              =
+            Delimiter . fromMaybe ',' . unHelpful . delimiter $ opts
+        minSize'            = fmap MinSize . unHelpful . minSize $ opts
+        numEigen'           = fmap NumEigen . unHelpful . numEigen $ opts
+        minModularity'      = fmap Q . unHelpful . minModularity $ opts
+        eigenGroup'         =
+          maybe SignGroup (readOrErr "Cannot read --eigen-group")
+            . unHelpful
+            . eigenGroup
+            $ opts
+        separateComponents' = unHelpful . separateComponents $ opts
+        outputTree'         = fmap OutputTree . unHelpful . outputTree $ opts
+        decodeOpt       = CSV.defaultDecodeOptions
+                            { CSV.decDelimiter =
+                                fromIntegral (ord . unDelimiter $ delim')
+                            }
+        encodeOpt       = CSV.defaultEncodeOptions
+                            { CSV.encDelimiter =
+                                fromIntegral (ord . unDelimiter $ delim')
+                            }
+
+    clusteringTree <-
+        case clusteringType' of
+            Dense -> do
+                (items, mat) <- readDenseAdjMatrix decodeOpt stdin
+
+                let cluster items = HD.hierarchicalSpectralCluster
+                                      eigenGroup'
+                                      (fmap unNumEigen numEigen')
+                                      (fmap unMinSize minSize')
+                                      minModularity'
+                                      items
+
+                return $
+                    if separateComponents'
+                        then Multiple
+                           . fmap (uncurry cluster)
+                           . getComponentMatsItems items
+                           $ mat
+                        else Single $ cluster items mat
+            Sparse -> do
+                (items, mat) <- readEigenSparseAdjMatrix decodeOpt stdin
+
+                let cluster items = HS.hierarchicalSpectralCluster
+                                      eigenGroup'
+                                      (fmap unNumEigen numEigen')
+                                      (fmap unMinSize minSize')
+                                      minModularity'
+                                      items
+
+                return $
+                    if separateComponents'
+                        then Multiple
+                           . fmap (uncurry cluster)
+                           . getComponentMatsItems items
+                           $ mat
+                        else Single $ cluster items mat
+
+    body <- case clusteringTree of
+        (Single ct) -> do
+            let clustering = zip ([1..] :: [Int]) . getClusterItemsTree $ ct
+                body :: [(T.Text, T.Text)]
+                body = concatMap
+                        (\(!c, xs) -> fmap (\ !x -> (x, showt c)) . V.toList $ xs)
+                        clustering
+
+            case outputTree' of
+                Nothing                -> return ()
+                Just (OutputTree file) -> B.writeFile file
+                                        . A.encodePretty
+                                        . clusteringTreeToDendrogram
+                                        $ ct
+
+            return body
+        (Multiple cts) -> do
+            let clustering =
+                    fmap (L.over L._2 (zip ([1..] :: [Int]) . getClusterItemsTree))
+                        . zip ([1..] :: [Int])
+                        $ cts
+                body :: [(T.Text, T.Text)]
+                body = concatMap
+                        (\ (!t, xs)
+                        -> concatMap (\ (!c, ys)
+                                     -> fmap (\ x -> (x, showt t <> "/" <> showt c))
+                                      . V.toList
+                                      $ ys
+                                     )
+                           xs
+                        )
+                        clustering
+
+            case outputTree' of
+                Nothing                -> return ()
+                Just (OutputTree file) -> do
+                    let getSize :: ClusteringTree a -> Int
+                        getSize = sum . fmap V.length . getClusterItemsTree
+                        getFileName :: Int -> Int -> String
+                        getFileName t n =
+                            uncurry (File.</>)
+                                . L.over L._2 (\x -> intercalate "_" ["tree", show t, "size", show n, x])
+                                . File.splitFileName
+                                $ file
+                        write :: (A.ToJSON a) => Int -> ClusteringTree a -> IO ()
+                        write t tree = do
+                            B.writeFile (getFileName t (getSize tree))
+                                . A.encodePretty
+                                . clusteringTreeToDendrogram
+                                $ tree
+
+                    mapM_ (uncurry write) . zip [1..] $ cts
+
+            return body
+
+    -- | Print final result.
+    B.putStr
+        . (<>) "item,cluster\n"
+        . CSV.encodeWith encodeOpt
+        $ body
+
+    return ()
diff --git a/hierarchical-spectral-clustering.cabal b/hierarchical-spectral-clustering.cabal
new file mode 100644
--- /dev/null
+++ b/hierarchical-spectral-clustering.cabal
@@ -0,0 +1,76 @@
+name:                hierarchical-spectral-clustering
+version:             0.2.1.0
+synopsis:            Hierarchical spectral clustering of a graph.
+description:         Generate a tree of hierarchical spectral clustering using Newman-Girvan modularity as a stopping criteria.
+homepage:            http://github.com/GregorySchwartz/hierarchical-spectral-clustering#readme
+license:             GPL-3
+license-file:        LICENSE
+author:              Gregory W. Schwartz
+maintainer:          gsch@pennmedicine.upenn.edu
+copyright:           2018 Gregory W. Schwartz
+category:            Bioinformatics
+build-type:          Simple
+-- extra-source-files:
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Math.Clustering.Hierarchical.Spectral.Dense
+                     , Math.Clustering.Hierarchical.Spectral.Sparse
+                     , Math.Clustering.Hierarchical.Spectral.Load
+                     , Math.Clustering.Hierarchical.Spectral.Eigen.AdjacencyMatrix
+                     , Math.Clustering.Hierarchical.Spectral.Eigen.FeatureMatrix
+                     , Math.Clustering.Hierarchical.Spectral.Types
+                     , Math.Clustering.Hierarchical.Spectral.Utility
+                     , Math.Graph.Components
+                     , Math.Graph.Types
+  other-modules:       Math.Clustering.Hierarchical.Spectral.Test
+  build-depends:       base >= 4.7 && < 5
+                     , aeson
+                     , cassava
+                     , clustering
+                     , containers
+                     , eigen == 3.3.4.1
+                     , hierarchical-clustering
+                     , hmatrix
+                     , fgl
+                     , managed
+                     , modularity
+                     , mtl
+                     , safe
+                     , sparse-linear-algebra
+                     , spectral-clustering
+                     , streaming
+                     , streaming-bytestring
+                     , streaming-cassava
+                     , streaming-with
+                     , text
+                     , tree-fun
+                     , vector
+  ghc-options:         -O2
+  default-language:    Haskell2010
+
+executable cluster-tree
+  hs-source-dirs:      app
+  main-is:             Main.hs
+  ghc-options:         -threaded -rtsopts -O2
+  build-depends:       base
+                     , hierarchical-spectral-clustering
+                     , aeson
+                     , aeson-pretty
+                     , bytestring
+                     , cassava
+                     , containers
+                     , filepath
+                     , hmatrix
+                     , lens
+                     , optparse-generic
+                     , safe
+                     , text
+                     , text-show
+                     , vector
+  default-language:    Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/GregorySchwartz/hierarchical-spectral-clustering
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Dense.hs b/src/Math/Clustering/Hierarchical/Spectral/Dense.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Dense.hs
@@ -0,0 +1,94 @@
+{- Math.Clustering.Hierarchical.Spectral
+Gregory W. Schwartz
+
+Collects the functions pertaining to hierarchical spectral clustering.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Dense
+    ( hierarchicalSpectralCluster
+    , AdjacencyMatrix (..)
+    , Items (..)
+    ) where
+
+-- Remote
+import Data.Bool (bool)
+import Data.Clustering.Hierarchical (Dendrogram (..))
+import Data.Maybe (fromMaybe)
+import Data.Tree (Tree (..))
+import Math.Clustering.Spectral.Dense (spectralClusterNorm, spectralClusterKNorm)
+import Math.Modularity.Dense (getModularity)
+import Math.Modularity.Types (Q (..))
+import qualified Data.Foldable as F
+import qualified Data.Set as Set
+import qualified Data.Vector as V
+import qualified Data.Vector.Storable as VS
+import qualified Numeric.LinearAlgebra as H
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Clustering.Hierarchical.Spectral.Utility
+
+type AdjacencyMatrix = H.Matrix Double
+type Items a         = V.Vector a
+
+-- | Check if there is more than one cluster.
+hasMultipleClusters :: H.Vector Double -> Bool
+hasMultipleClusters = (> 1) . Set.size . Set.fromList . H.toList
+
+-- | Generates a tree through divisive hierarchical clustering using
+-- Newman-Girvan modularity as a stopping criteria. Can also use minimum number
+-- of observations in a cluster as the stopping criteria.
+hierarchicalSpectralCluster :: (Show a) => EigenGroup
+                            -> Maybe NumEigen
+                            -> Maybe Int
+                            -> Maybe Q
+                            -> Items a
+                            -> AdjacencyMatrix
+                            -> ClusteringTree a
+hierarchicalSpectralCluster !eigenGroup !numEigenMay !minSizeMay !minModMay !items !adjMat =
+    if H.rows adjMat > 1
+        && hasMultipleClusters clusters
+        && ngMod > minMod
+        && H.rows left >= minSize
+        && H.rows right >= minSize
+        then
+            Node { rootLabel = vertex
+                 , subForest =
+                    [ hierarchicalSpectralCluster
+                        eigenGroup
+                        numEigenMay
+                        minSizeMay
+                        minModMay
+                        (subsetVector items leftIdxs)
+                        left
+                    , hierarchicalSpectralCluster
+                        eigenGroup
+                        numEigenMay
+                        minSizeMay
+                        minModMay
+                        (subsetVector items rightIdxs)
+                        right
+                    ]
+                 }
+        else
+            Node {rootLabel = vertex, subForest = []}
+  where
+    minMod      = fromMaybe (Q 0) minModMay
+    minSize     = fromMaybe 1 minSizeMay
+    numEigen    = fromMaybe 1 numEigenMay
+    vertex      = ClusteringVertex { _clusteringItems = items
+                                   , _ngMod = ngMod
+                                   }
+    clusters    = spectralClustering eigenGroup adjMat
+    spectralClustering :: EigenGroup -> AdjacencyMatrix -> H.Vector Double
+    spectralClustering SignGroup   = spectralClusterNorm
+    spectralClustering KMeansGroup = spectralClusterKNorm numEigen 2
+    ngMod       = getModularity clusters $ adjMat
+    getIdxs val = VS.ifoldr' (\ !i !v !acc -> bool acc (i:acc) $ v == val) []
+    leftIdxs    = getIdxs 0 $ clusters
+    rightIdxs   = getIdxs 1 $ clusters
+    left        = adjMat H.?? (H.Pos (H.idxs leftIdxs), H.Pos (H.idxs leftIdxs))
+    right       =
+        adjMat H.?? (H.Pos (H.idxs rightIdxs), H.Pos (H.idxs rightIdxs))
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Eigen/AdjacencyMatrix.hs b/src/Math/Clustering/Hierarchical/Spectral/Eigen/AdjacencyMatrix.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Eigen/AdjacencyMatrix.hs
@@ -0,0 +1,100 @@
+{- Math.Clustering.Hierarchical.Spectral.Eigen.AdjacencyMatrix
+Gregory W. Schwartz
+
+Collects the functions pertaining to hierarchical spectral clustering.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Eigen.AdjacencyMatrix
+    ( hierarchicalSpectralCluster
+    , AdjacencyMatrix (..)
+    , Items (..)
+    ) where
+
+-- Remote
+import Data.Bool (bool)
+import Data.Clustering.Hierarchical (Dendrogram (..))
+import Data.Maybe (fromMaybe)
+import Data.Tree (Tree (..))
+import Math.Clustering.Spectral.Eigen.AdjacencyMatrix (spectralClusterNorm, spectralClusterKNorm)
+import Math.Modularity.Eigen.Sparse (getModularity)
+import Math.Modularity.Types (Q (..))
+import Safe (headMay)
+import qualified Data.Foldable as F
+import qualified Data.Set as Set
+import qualified Data.Eigen.SparseMatrix as S
+import qualified Data.Vector as V
+import qualified Data.Vector.Storable as VS
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Clustering.Hierarchical.Spectral.Utility
+
+type AdjacencyMatrix = S.SparseMatrixXd
+type Items a         = V.Vector a
+
+-- | Check if there is more than one cluster.
+hasMultipleClusters :: S.SparseMatrixXd -> Bool
+hasMultipleClusters = (> 1)
+                    . Set.size
+                    . Set.fromList
+                    . concat
+                    . S.toDenseList
+
+-- | Generates a tree through divisive hierarchical clustering using
+-- Newman-Girvan modularity as a stopping criteria. Can also use minimum number
+-- of observations in a cluster as the stopping criteria.
+hierarchicalSpectralCluster :: EigenGroup
+                            -> Maybe NumEigen
+                            -> Maybe Int
+                            -> Maybe Q
+                            -> Items a
+                            -> AdjacencyMatrix
+                            -> ClusteringTree a
+hierarchicalSpectralCluster !eigenGroup !numEigenMay !minSizeMay !minModMay !items !adjMat =
+
+    if S.rows adjMat > 1
+        && hasMultipleClusters clusters
+        && ngMod > minMod
+        && S.rows left >= minSize
+        && S.rows right >= minSize
+        then do
+            Node { rootLabel = vertex
+                 , subForest = [ hierarchicalSpectralCluster
+                                  eigenGroup
+                                  numEigenMay
+                                  minSizeMay
+                                  minModMay
+                                  (subsetVector items leftIdxs)
+                                  left
+                               , hierarchicalSpectralCluster
+                                  eigenGroup
+                                  numEigenMay
+                                  minSizeMay
+                                  minModMay (subsetVector items rightIdxs)
+                                  right
+                               ]
+                 }
+        else
+            Node {rootLabel = vertex, subForest = []}
+  where
+    clusters = spectralClustering eigenGroup adjMat
+    spectralClustering :: EigenGroup -> AdjacencyMatrix -> S.SparseMatrixXd
+    spectralClustering SignGroup   = spectralClusterNorm
+    spectralClustering KMeansGroup = spectralClusterKNorm numEigen 2
+    minMod      = fromMaybe (Q 0) minModMay
+    minSize     = fromMaybe 1 minSizeMay
+    numEigen    = fromMaybe 1 numEigenMay
+    vertex      = ClusteringVertex { _clusteringItems = items
+                                   , _ngMod = ngMod
+                                   }
+    ngMod       = getModularity clusters adjMat
+    getIdxs val = VS.ifoldr' (\ !i !v !acc -> bool acc (i:acc) $ v == val) []
+                . VS.fromList
+                . concat
+                . S.toDenseList
+    leftIdxs    = getIdxs 0 clusters
+    rightIdxs   = getIdxs 1 clusters
+    left        = S.squareSubset leftIdxs adjMat
+    right       = S.squareSubset rightIdxs adjMat
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Eigen/FeatureMatrix.hs b/src/Math/Clustering/Hierarchical/Spectral/Eigen/FeatureMatrix.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Eigen/FeatureMatrix.hs
@@ -0,0 +1,113 @@
+{- Math.Clustering.Hierarchical.Spectral.Eigen.FeatureMatrix
+Gregory W. Schwartz
+
+Collects the functions pertaining to hierarchical spectral clustering for
+feature matrices.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Eigen.FeatureMatrix
+    ( hierarchicalSpectralCluster
+    , FeatureMatrix (..)
+    , B (..)
+    , Items (..)
+    , ShowB (..)
+    ) where
+
+-- Remote
+import Data.Bool (bool)
+import Data.Clustering.Hierarchical (Dendrogram (..))
+import Data.Maybe (fromMaybe)
+import Data.Tree (Tree (..))
+import Math.Clustering.Spectral.Eigen.FeatureMatrix (B (..), getB, spectralCluster, spectralClusterK)
+import Math.Modularity.Eigen.Sparse (getBModularity)
+import Math.Modularity.Types (Q (..))
+import qualified Data.Foldable as F
+import qualified Data.Set as Set
+import qualified Data.Eigen.SparseMatrix as S
+import qualified Data.Vector as V
+import qualified Data.Vector.Storable as VS
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Clustering.Hierarchical.Spectral.Utility
+
+type FeatureMatrix   = S.SparseMatrixXd
+type Items a         = V.Vector a
+type ShowB           = ((Int, Int), [(Int, Int, Double)])
+type NormalizeFlag   = Bool
+
+-- | Check if there is more than one cluster.
+hasMultipleClusters :: S.SparseMatrixXd -> Bool
+hasMultipleClusters = (> 1)
+                    . Set.size
+                    . Set.fromList
+                    . concat
+                    . S.toDenseList
+
+-- | Generates a tree through divisive hierarchical clustering using
+-- Newman-Girvan modularity as a stopping criteria. Can use minimum number of
+-- observations in a cluster as a stopping criteria. Assumes the feature matrix
+-- has column features and row observations. Items correspond to rows. Can
+-- use FeatureMatrix or a pre-generated B matrix. See Shu et al., "Efficient
+-- Spectral Neighborhood Blocking for Entity Resolution", 2011.
+hierarchicalSpectralCluster :: EigenGroup
+                            -> NormalizeFlag
+                            -> Maybe NumEigen
+                            -> Maybe Int
+                            -> Maybe Q
+                            -> Items a
+                            -> Either FeatureMatrix B
+                            -> ClusteringTree a
+hierarchicalSpectralCluster eigenGroup normFlag numEigenMay minSizeMay minModMay initItems initMat =
+    go initItems initB
+  where
+    initB = either (getB normFlag) id $ initMat
+    minMod      = fromMaybe (Q 0) minModMay
+    minSize     = fromMaybe 1 minSizeMay
+    numEigen    = fromMaybe 1 numEigenMay
+    go :: Items a -> B -> ClusteringTree a
+    go !items !b =
+        if (S.rows $ unB b) > 1
+            && hasMultipleClusters clusters
+            && ngMod > minMod
+            && S.rows (unB left) >= minSize
+            && S.rows (unB right) >= minSize
+            then
+                Node { rootLabel = vertex
+                     , subForest = [ go (subsetVector items leftIdxs) left
+                                   , go (subsetVector items rightIdxs) right
+                                   ]
+                     }
+
+            else
+                Node {rootLabel = vertex, subForest = []}
+      where
+        vertex      = ClusteringVertex
+                        { _clusteringItems = items
+                        , _ngMod = ngMod
+                        }
+        clusters :: S.SparseMatrixXd
+        clusters = spectralClustering eigenGroup b
+        spectralClustering :: EigenGroup -> B -> S.SparseMatrixXd
+        spectralClustering SignGroup   = spectralCluster
+        spectralClustering KMeansGroup = spectralClusterK numEigen 2
+        ngMod :: Q
+        ngMod = getBModularity clusters b
+        getSortedIdxs :: Double -> S.SparseMatrixXd -> [Int]
+        getSortedIdxs val = VS.ifoldr' (\ !i !v !acc -> bool acc (i:acc) $ v == val) []
+                          . VS.fromList
+                          . concat
+                          . S.toDenseList
+        leftIdxs :: [Int]
+        leftIdxs    = getSortedIdxs 0 clusters
+        rightIdxs :: [Int]
+        rightIdxs   = getSortedIdxs 1 clusters
+        left :: B
+        left        = B $ extractRows (unB b) leftIdxs
+        right :: B
+        right       = B $ extractRows (unB b) rightIdxs
+        extractRows :: S.SparseMatrixXd -> [Int] -> S.SparseMatrixXd
+        extractRows mat [] = S.fromList 0 0 []
+        extractRows mat xs = S.fromRows . fmap (flip S.getRow mat) $ xs
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Load.hs b/src/Math/Clustering/Hierarchical/Spectral/Load.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Load.hs
@@ -0,0 +1,167 @@
+{- Math.Clustering.Hierarchical.Spectral.Load
+Gregory W. Schwartz
+
+Collects the functions pertaining to loading a matrix.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Math.Clustering.Hierarchical.Spectral.Load
+    ( readDenseAdjMatrix
+    , readSparseAdjMatrix
+    , readEigenSparseAdjMatrix
+    ) where
+
+-- Remote
+import Control.Monad.Except (runExceptT, ExceptT (..))
+import Control.Monad.Managed (with, liftIO, Managed (..))
+import Data.Maybe (fromMaybe, catMaybes)
+import System.IO (Handle (..))
+import qualified Data.ByteString.Streaming.Char8 as BS
+import qualified Data.Csv as CSV
+import qualified Data.Eigen.SparseMatrix as E
+import qualified Data.Map.Strict as Map
+import qualified Data.Set as Set
+import qualified Data.Sparse.Common as SH
+import qualified Data.Text as T
+import qualified Data.Vector as V
+import qualified Numeric.LinearAlgebra as H
+import qualified Streaming as S
+import qualified Streaming.Cassava as S
+import qualified Streaming.Prelude as S
+import qualified Streaming.With.Lifted as SW
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+
+-- | Generic error message.
+errorMsg = error "Not correct format (requires row,column,value)"
+
+-- | Parse a row of a label index file.
+parseRow :: (T.Text, T.Text, Double) -> ((T.Text, T.Text), Double)
+parseRow (i, j, v) = ((i, j), v)
+
+-- | Ignore the disconnected vertices, not used (rather use very small weight).
+ignoreDisconnected :: V.Vector T.Text
+                   -> H.Matrix Double
+                   -> (V.Vector T.Text, H.Matrix Double)
+ignoreDisconnected items mat = (newItems, newMat)
+  where
+    newItems = V.fromList $ fmap ((V.!) items) valid
+    newMat = mat H.?? (H.Pos $ H.idxs valid, H.Pos $ H.idxs valid)
+    valid = catMaybes
+          . zipWith (\x xs -> if sum xs > 0 then Just x else Nothing) [0..]
+          . H.toLists
+          $ mat
+
+-- | Ensure symmetry.
+symmetric :: [((Int, Int), Double)] -> [((Int, Int), Double)]
+symmetric = concatMap (\((!i, !j), v) -> [((i, j), v), ((j, i), v)])
+
+-- | Ensure zeros on diagonal.
+zeroDiag :: [((Int, Int), Double)] -> [((Int, Int), Double)]
+zeroDiag = filter (\((!i, !j), _) -> i /= j)
+
+-- | Get the translated matrix indices.
+getNewIndices
+    -- :: (Eq a, Ord a)
+    -- => [((a, a), Double)] -> [((Int, Int), Double)]
+    :: [((T.Text, T.Text), Double)] -> [((Int, Int), Double)]
+getNewIndices xs =
+    fmap
+        (\((!i,!j),!v) ->
+              ( ( Map.findWithDefault eMsg i idxMap
+                , Map.findWithDefault eMsg j idxMap
+                )
+              , v
+              )
+        )
+        xs
+  where
+    eMsg     = error "Index not found during index conversion."
+    indices  = getAllIndices xs
+    idxMap   = Map.fromList $ zip indices [0 ..]
+
+-- | Get the list of all indices.
+getAllIndices :: (Eq a, Ord a) => [((a, a), Double)] -> [a]
+getAllIndices xs = Set.toAscList . Set.union (getSet fst) $ getSet snd
+  where
+    getSet f = Set.fromList . fmap (f . fst) $ xs
+
+-- | Get a dense adjacency matrix from a handle.
+readDenseAdjMatrix :: CSV.DecodeOptions
+                   -> Handle
+                   -> IO (V.Vector T.Text, H.Matrix Double)
+readDenseAdjMatrix decodeOpt handle = flip with return $ do
+    let getAssocList = S.toList_ . S.map parseRow
+
+    assocList <-
+        fmap (either (error . show) id)
+            . runExceptT
+            . getAssocList
+            . S.decodeWith decodeOpt S.NoHeader
+            $ (BS.hGetContents handle :: BS.ByteString (ExceptT S.CsvParseException Managed) ())
+
+    let items = V.fromList $ getAllIndices assocList
+        mat   = H.assoc (V.length items, V.length items) 0
+              . Set.toList
+              . Set.fromList -- Ensure no duplicates.
+              . symmetric -- Ensure symmetry.
+              . zeroDiag -- Ensure zeros on diagonal.
+              . getNewIndices -- Only look at present rows by converting indices.
+              $ assocList
+
+    return (items, mat)
+
+-- | Get a sparse adjacency matrix from a handle.
+readSparseAdjMatrix :: CSV.DecodeOptions
+                    -> Handle
+                    -> IO (V.Vector T.Text, SH.SpMatrix Double)
+readSparseAdjMatrix decodeOpt handle = flip with return $ do
+    let getAssocList = S.toList_ . S.map parseRow
+
+    assocList <-
+        fmap (either (error . show) id)
+            . runExceptT
+            . getAssocList
+            . S.decodeWith decodeOpt S.NoHeader
+            $ (BS.hGetContents handle :: BS.ByteString (ExceptT S.CsvParseException Managed) ())
+
+    let items = V.fromList $ getAllIndices assocList
+        mat   = SH.fromListSM (V.length items, V.length items)
+              . Set.toList
+              . Set.fromList -- Ensure no duplicates.
+              . fmap (\((i, j), v) -> (i, j, v))
+              . symmetric -- Ensure symmetry.
+              . zeroDiag -- Ensure zeros on diagonal.
+              . getNewIndices -- Only look at present rows by converting indices.
+              $ assocList
+
+    return (items, mat)
+
+-- | Get a sparse adjacency matrix from a handle.
+readEigenSparseAdjMatrix :: CSV.DecodeOptions
+                    -> Handle
+                    -> IO (V.Vector T.Text, E.SparseMatrixXd)
+readEigenSparseAdjMatrix decodeOpt handle = flip with return $ do
+    let getAssocList = S.toList_ . S.map parseRow
+
+    assocList <-
+        fmap (either (error . show) id)
+            . runExceptT
+            . getAssocList
+            . S.decodeWith decodeOpt S.NoHeader
+            $ (BS.hGetContents handle :: BS.ByteString (ExceptT S.CsvParseException Managed) ())
+
+    let items = V.fromList $ getAllIndices assocList
+        mat   = E.fromList (V.length items) (V.length items)
+              . Set.toList
+              . Set.fromList -- Ensure no duplicates.
+              . fmap (\((i, j), v) -> (i, j, v))
+              . symmetric -- Ensure symmetry.
+              . zeroDiag -- Ensure zeros on diagonal.
+              . getNewIndices -- Only look at present rows by converting indices.
+              $ assocList
+
+    return (items, mat)
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Sparse.hs b/src/Math/Clustering/Hierarchical/Spectral/Sparse.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Sparse.hs
@@ -0,0 +1,177 @@
+{- Math.Clustering.Hierarchical.Spectral.Sparse
+Gregory W. Schwartz
+
+Collects the functions pertaining to hierarchical spectral clustering for sparse
+data.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Sparse
+    ( hierarchicalSpectralCluster
+    , hierarchicalSpectralClusterAdj
+    , FeatureMatrix (..)
+    , B (..)
+    , Items (..)
+    , ShowB (..)
+    ) where
+
+-- Remote
+import Data.Bool (bool)
+import Data.Clustering.Hierarchical (Dendrogram (..))
+import Data.Maybe (fromMaybe)
+import Data.Tree (Tree (..))
+import Math.Clustering.Spectral.Sparse (B (..), AdjacencyMatrix (..), getB, spectralCluster, spectralClusterK, spectralClusterNorm, spectralClusterKNorm)
+import Math.Modularity.Sparse (getBModularity, getModularity)
+import Math.Modularity.Types (Q (..))
+import qualified Data.Foldable as F
+import qualified Data.Set as Set
+import qualified Data.Sparse.Common as S
+import qualified Data.Vector as V
+import qualified Data.Vector.Storable as VS
+import qualified Numeric.LinearAlgebra.Sparse as S
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Clustering.Hierarchical.Spectral.Utility
+
+type FeatureMatrix   = S.SpMatrix Double
+type Items a         = V.Vector a
+type ShowB           = ((Int, Int), [(Int, Int, Double)])
+type NormalizeFlag   = Bool
+
+-- | Check if there is more than one cluster.
+hasMultipleClusters :: S.SpVector Double -> Bool
+hasMultipleClusters = (> 1) . Set.size . Set.fromList . S.toDenseListSV
+
+-- | Generates a tree through divisive hierarchical clustering using
+-- Newman-Girvan modularity as a stopping criteria. Can use minimum number of
+-- observations in a cluster as a stopping criteria. Assumes the feature matrix
+-- has column features and row observations. Items correspond to rows. Can
+-- use FeatureMatrix or a pre-generated B matrix. See Shu et al., "Efficient
+-- Spectral Neighborhood Blocking for Entity Resolution", 2011.
+hierarchicalSpectralCluster :: EigenGroup
+                            -> NormalizeFlag
+                            -> Maybe NumEigen
+                            -> Maybe Int
+                            -> Maybe Q
+                            -> Items a
+                            -> Either FeatureMatrix B
+                            -> ClusteringTree a
+hierarchicalSpectralCluster eigenGroup normFlag numEigenMay minSizeMay minModMay initItems initMat =
+    go initItems initB
+  where
+    initB = either (getB normFlag) id $ initMat
+    minMod   = fromMaybe (Q 0) minModMay
+    minSize  = fromMaybe 1 minSizeMay
+    numEigen = fromMaybe 1 numEigenMay
+    go :: Items a -> B -> ClusteringTree a
+    go !items !b =
+        if (S.nrows $ unB b) > 1
+            && hasMultipleClusters clusters
+            && ngMod > minMod
+            && S.nrows (unB left) >= minSize
+            && S.nrows (unB right) >= minSize
+            then
+                Node { rootLabel = vertex
+                     , subForest = [ go (subsetVector items leftIdxs) left
+                                   , go (subsetVector items rightIdxs) right
+                                   ]
+                     }
+
+            else
+                Node {rootLabel = vertex, subForest = []}
+      where
+        vertex      = ClusteringVertex
+                        { _clusteringItems = items
+                        , _ngMod = ngMod
+                        }
+        clusters :: S.SpVector Double
+        clusters = spectralClustering eigenGroup b
+        spectralClustering :: EigenGroup -> B -> S.SpVector Double
+        spectralClustering SignGroup   = spectralCluster
+        spectralClustering KMeansGroup = spectralClusterK numEigen 2
+        ngMod :: Q
+        ngMod       = getBModularity clusters $ b
+        getSortedIdxs :: Double -> S.SpVector Double -> [Int]
+        getSortedIdxs val = VS.ifoldr' (\ !i !v !acc -> bool acc (i:acc) $ v == val) []
+                          . VS.fromList
+                          . S.toDenseListSV
+        leftIdxs :: [Int]
+        leftIdxs    = getSortedIdxs 0 $ clusters
+        rightIdxs :: [Int]
+        rightIdxs   = getSortedIdxs 1 $ clusters
+        left :: B
+        left        = B $ extractRows (unB b) leftIdxs
+        right :: B
+        right       = B $ extractRows (unB b) rightIdxs
+        extractRows :: S.SpMatrix Double -> [Int] -> S.SpMatrix Double
+        extractRows mat [] = S.zeroSM 0 0
+        extractRows mat xs =
+          S.transposeSM . S.fromColsL . fmap (S.extractRow mat) $ xs
+
+-- | Generates a tree through divisive hierarchical clustering using
+-- Newman-Girvan modularity as a stopping criteria. Can use minimum number of
+-- observations in a cluster as a stopping criteria. Uses an adjacency matrix.
+-- Items correspond to rows.
+hierarchicalSpectralClusterAdj :: EigenGroup
+                               -> Maybe NumEigen
+                               -> Maybe Int
+                               -> Maybe Q
+                               -> Items a
+                               -> AdjacencyMatrix
+                               -> ClusteringTree a
+hierarchicalSpectralClusterAdj eigenGroup numEigenMay minSizeMay minModMay initItems initMat =
+    go initItems initMat
+  where
+    minMod      = fromMaybe (Q 0) minModMay
+    minSize     = fromMaybe 1 minSizeMay
+    numEigen    = fromMaybe 1 numEigenMay
+    go :: Items a -> AdjacencyMatrix -> ClusteringTree a
+    go !items !mat =
+        if S.nrows mat > 1
+            && hasMultipleClusters clusters
+            && ngMod > minMod
+            && S.nrows left >= minSize
+            && S.nrows right >= minSize
+            then
+                Node { rootLabel = vertex
+                     , subForest = [ go (subsetVector items leftIdxs) left
+                                   , go (subsetVector items rightIdxs) right
+                                   ]
+                     }
+
+            else
+                Node {rootLabel = vertex, subForest = []}
+      where
+        vertex      = ClusteringVertex
+                        { _clusteringItems = items
+                        , _ngMod = ngMod
+                        }
+        clusters :: S.SpVector Double
+        clusters = spectralClustering eigenGroup mat
+        spectralClustering :: EigenGroup -> AdjacencyMatrix -> S.SpVector Double
+        spectralClustering SignGroup   = spectralClusterNorm
+        spectralClustering KMeansGroup = spectralClusterKNorm numEigen 2
+        ngMod :: Q
+        ngMod = getModularity clusters mat
+        getSortedIdxs :: Double -> S.SpVector Double -> [Int]
+        getSortedIdxs val = VS.ifoldr' (\ !i !v !acc -> bool acc (i:acc) $ v == val) []
+                          . VS.fromList
+                          . S.toDenseListSV
+        leftIdxs :: [Int]
+        leftIdxs    = getSortedIdxs 0 clusters
+        rightIdxs :: [Int]
+        rightIdxs   = getSortedIdxs 1 clusters
+        left :: AdjacencyMatrix
+        left        = getSubMat mat leftIdxs
+        right :: AdjacencyMatrix
+        right       = getSubMat mat rightIdxs
+        getSubMat :: S.SpMatrix Double -> [Int] -> S.SpMatrix Double
+        getSubMat mat [] = S.zeroSM 0 0
+        getSubMat mat is = S.fromColsL
+                         . (\x -> fmap (S.extractCol x) is)
+                         . S.transposeSM
+                         . S.fromColsL
+                         . fmap (S.extractRow mat)
+                         $ is
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Test.hs b/src/Math/Clustering/Hierarchical/Spectral/Test.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Test.hs
@@ -0,0 +1,188 @@
+{- Math.Clustering.Hierarchical.Spectral.Test
+Gregory W. Schwartz
+
+Collects the functions pertaining to testing hierarchical spectral clustering.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Test where
+
+-- Remote
+import Data.List (tails)
+import Data.Maybe (fromMaybe)
+import Data.Monoid ((<>))
+import Math.Clustering.Spectral.Sparse (getB, B (..))
+import qualified Data.Map.Strict as Map
+import qualified Data.Set as Set
+import qualified Data.Sparse.Common as S
+import qualified Data.Eigen.SparseMatrix as E
+import qualified Data.Vector as V
+import qualified Math.Clustering.Spectral.Eigen.FeatureMatrix as EF
+import qualified Numeric.LinearAlgebra as H
+
+-- Local
+import Math.Clustering.Hierarchical.Spectral.Types
+import Math.Clustering.Hierarchical.Spectral.Sparse
+import qualified Math.Clustering.Hierarchical.Spectral.Dense as Dense
+import qualified Math.Clustering.Hierarchical.Spectral.Eigen.FeatureMatrix as EF
+import qualified Math.Clustering.Hierarchical.Spectral.Eigen.AdjacencyMatrix as EA
+
+newtype QGram = QGram { unQGram :: String } deriving (Eq, Ord, Read, Show)
+newtype QGramMap = QGramMap
+    { unQGramMap :: Map.Map QGram Int
+    } deriving (Eq,Ord,Read,Show)
+
+exampleData :: [String]
+exampleData = [ "600 MOUNTAIN AVENUE"
+              , "700 MOUNTAIN AVE"
+              , "600-700 MOUNTAIN AVE"
+              , "100 DIAMOND HILL RD"
+              , "100 DIAMOND HILL ROAD"
+              , "123 SPRINGFIELD AVENUE"
+              , "123 SPRINFGIELD AVE"
+              ]
+
+exampleItems :: V.Vector String
+exampleItems = V.fromList exampleData
+
+-- | Add beginning and ending symbols.
+addBorders :: String -> String
+addBorders x = "##" <> x <> "$$"
+
+-- | Generate qgrams for a string.
+getQGrams :: Int -> String -> [QGram]
+getQGrams n =
+    fmap QGram . filter ((== n) . length) . fmap (take n) . tails . addBorders
+
+-- | Get mapping of qgrams to indices.
+getQGramMap :: [QGram] -> QGramMap
+getQGramMap = QGramMap . Map.fromList . flip zip [0,1..]
+
+-- | Convert a record to a vector.
+recordToRow :: Int -> QGramMap -> String -> S.SpVector Double
+recordToRow n (QGramMap qgramMap) = S.fromListSV (Map.size qgramMap)
+                                  . Map.toAscList
+                                  . Map.fromListWith (+)
+                                  . flip zip [1,1..]
+                                  . fromMaybe (error "Invalid qgram.")
+                                  . mapM (flip Map.lookup qgramMap)
+                                  . getQGrams n
+
+-- | Generate the matrix of qgrams from a list of records and qgram length.
+exampleMatrix :: Int -> [String] -> S.SpMatrix Double
+exampleMatrix n records =
+    S.transposeSM . S.fromColsL . fmap (recordToRow n qgramMap) $ records
+  where
+    qgramMap = getQGramMap
+             . Set.toList
+             . Set.fromList
+             . concatMap (getQGrams n)
+             $ records
+
+clusterExample = hierarchicalSpectralCluster
+                    SignGroup
+                    True
+                    Nothing
+                    Nothing
+                    Nothing
+                    exampleItems
+                    (Left $ exampleMatrix 3 exampleData)
+
+clusterKExample = hierarchicalSpectralCluster
+                    KMeansGroup
+                    True
+                    (Just 2)
+                    Nothing
+                    Nothing
+                    exampleItems
+                    (Left $ exampleMatrix 3 exampleData)
+
+clusterAdjExample = hierarchicalSpectralClusterAdj
+                        SignGroup
+                        Nothing
+                        Nothing
+                        Nothing
+                        exampleItems
+                        adjacencyExample
+
+clusterKAdjExample = hierarchicalSpectralClusterAdj
+                        KMeansGroup
+                        (Just 2)
+                        Nothing
+                        Nothing
+                        exampleItems
+                        adjacencyExample
+
+adjacencyExample :: S.SpMatrix Double
+adjacencyExample = S.filterSM (\i j _ -> i /= j) $ (unB b) S.##^ (unB b)
+  where
+    b = getB True $ exampleMatrix 3 exampleData
+
+denseAdjacencyExample :: H.Matrix Double
+denseAdjacencyExample = H.assoc (S.dimSM adjacencyExample) 0
+                      . fmap (\(!x, !y, !z) -> if x == y then ((x, y), 0) else ((x, y), z))
+                      . S.toListSM
+                      $ adjacencyExample
+
+denseClusterExample = Dense.hierarchicalSpectralCluster
+                        SignGroup
+                        Nothing
+                        Nothing
+                        Nothing
+                        exampleItems
+                        denseAdjacencyExample
+
+denseClusterKExample = Dense.hierarchicalSpectralCluster
+                        KMeansGroup
+                        (Just 2)
+                        Nothing
+                        Nothing
+                        exampleItems
+                        denseAdjacencyExample
+
+-- | Generate the matrix of qgrams from a list of records and qgram length.
+exampleEigenMatrix :: Int -> [String] -> E.SparseMatrixXd
+exampleEigenMatrix n records = E.fromList (S.nrows mat) (S.ncols mat) . S.toListSM $ mat
+  where
+    mat = exampleMatrix n records
+
+adjacencyEigenExample :: E.SparseMatrixXd
+adjacencyEigenExample = E._imap (\i j v -> if i == j then 0 else v)
+                      $ (EF.unB b) * E.transpose (EF.unB b)
+  where
+    b = EF.getB True $ exampleEigenMatrix 3 exampleData
+
+clusterEigenExample = EF.hierarchicalSpectralCluster
+                        SignGroup
+                        True
+                        Nothing
+                        Nothing
+                        Nothing
+                        exampleItems
+                        (Left $ exampleEigenMatrix 3 exampleData)
+
+clusterKEigenExample = EF.hierarchicalSpectralCluster
+                        KMeansGroup
+                        True
+                        (Just 2)
+                        Nothing
+                        Nothing
+                        exampleItems
+                        (Left $ exampleEigenMatrix 3 exampleData)
+
+clusterAdjEigenExample = EA.hierarchicalSpectralCluster
+                            SignGroup
+                            Nothing
+                            Nothing
+                            Nothing
+                            exampleItems
+                            adjacencyEigenExample
+
+clusterKAdjEigenExample = EA.hierarchicalSpectralCluster
+                        KMeansGroup
+                        (Just 2)
+                        Nothing
+                        Nothing
+                        exampleItems
+                        adjacencyEigenExample
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Types.hs b/src/Math/Clustering/Hierarchical/Spectral/Types.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Types.hs
@@ -0,0 +1,90 @@
+{- Math.Clustering.Hierarchical.Types
+Gregory W. Schwartz
+
+Collects the types used in hierarchical clustering.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE StandaloneDeriving #-}
+
+module Math.Clustering.Hierarchical.Spectral.Types
+    ( ClusteringTree (..)
+    , ClusteringVertex (..)
+    , EigenGroup (..)
+    , clusteringTreeToDendrogram
+    , clusteringTreeToDendrogramCumulative
+    , getClusterItemsDend
+    , getClusterItemsTree
+    , Q (..)
+    , NumEigen (..)
+    ) where
+
+-- Remote
+import Data.Clustering.Hierarchical (Dendrogram (..))
+import Data.Monoid ((<>))
+import Data.Tree (Tree (..))
+import GHC.Generics (Generic)
+import Math.Modularity.Types (Q (..))
+import Math.TreeFun.Tree (leaves)
+import qualified Data.Aeson as A
+import qualified Data.Foldable as F
+import qualified Data.Vector as V
+
+-- Local
+
+type Items a         = V.Vector a
+type ClusteringTree a = Tree (ClusteringVertex a)
+type NumEigen = Int
+
+data EigenGroup = SignGroup | KMeansGroup deriving (Read, Show, Generic)
+
+data ClusteringVertex a = ClusteringVertex
+    { _clusteringItems  :: !(Items a)
+    , _ngMod            :: !Q
+    } deriving (Eq, Ord, Read, Show, Generic)
+
+-- | Convert a ClusteringTree to a Dendrogram. Modularity is the distance.
+clusteringTreeToDendrogram :: ClusteringTree a -> Dendrogram (Items a)
+clusteringTreeToDendrogram = go
+  where
+    go (Node { rootLabel = !n, subForest = []}) = Leaf $ _clusteringItems n
+    go (Node { rootLabel = !n, subForest = [x, y]}) =
+        Branch (unQ . _ngMod $ n) (go x) (go y)
+    go (Node { subForest = xs}) =
+        error $ "Clustering tree has "
+            <> (show $ length xs)
+            <> " children. Requires two or none."
+
+-- | Convert a ClusteringTree to a Dendrogram. Modularity is the distance, such
+-- that the distance is the modularity plus the maximum distance of each branch.
+clusteringTreeToDendrogramCumulative :: ClusteringTree a -> Dendrogram (Items a)
+clusteringTreeToDendrogramCumulative = fst . go
+  where
+    go (Node { rootLabel = !n, subForest = []}) =
+        (Leaf (_clusteringItems n), 0)
+    go (Node { rootLabel = !n, subForest = [x, y]}) =
+        (Branch newD l r, newD)
+      where
+        newD = (unQ . _ngMod $ n) + max lDist rDist
+        (!l, !lDist) = go x
+        (!r, !rDist) = go y
+    go (Node { subForest = xs}) =
+        error $ "Clustering tree has "
+            <> (show $ length xs)
+            <> " children. Requires two or none."
+
+-- | Gather clusters (leaves) from the dendrogram.
+getClusterItemsDend :: Foldable t => t (Items a) -> [Items a]
+getClusterItemsDend = F.toList
+
+-- | Gather clusters (leaves) from the tree.
+getClusterItemsTree :: ClusteringTree a -> [Items a]
+getClusterItemsTree = fmap _clusteringItems . leaves
+
+deriving instance (Read a) => Read (Dendrogram a)
+deriving instance Generic (Dendrogram a)
+
+instance (A.ToJSON a) => A.ToJSON (Dendrogram a) where
+    toEncoding = A.genericToEncoding A.defaultOptions
+instance (A.FromJSON a) => A.FromJSON (Dendrogram a)
diff --git a/src/Math/Clustering/Hierarchical/Spectral/Utility.hs b/src/Math/Clustering/Hierarchical/Spectral/Utility.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Clustering/Hierarchical/Spectral/Utility.hs
@@ -0,0 +1,28 @@
+{- Math.Clustering.Hierarchical.Spectral.Utility
+Gregory W. Schwartz
+
+Collects utility functions for the clustering section of the program.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Clustering.Hierarchical.Spectral.Utility
+  ( subsetVector
+  ) where
+
+-- Remote
+import Data.Maybe (fromMaybe)
+import qualified Data.Foldable as F
+import qualified Data.Vector as V
+
+-- Local
+
+
+subsetVector :: V.Vector a -> [Int] -> V.Vector a
+subsetVector xs =
+    V.fromList
+        . F.foldr' (\ !i !acc
+                    -> ( fromMaybe (error "Out of bounds in subsetVector.")
+                      $ xs V.!? i
+                      ) : acc
+                    ) []
diff --git a/src/Math/Graph/Components.hs b/src/Math/Graph/Components.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Graph/Components.hs
@@ -0,0 +1,37 @@
+{- Math.Graph.Components
+Gregory W. Schwartz
+
+Find connected components of matrices.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+
+module Math.Graph.Components
+  ( getComponentMats
+  , getComponentMatsItems
+  ) where
+
+-- Remote
+import Data.List (sort)
+import qualified Data.Graph.Inductive as G
+import qualified Data.Vector as V
+
+-- Local
+import Math.Graph.Types
+import Math.Clustering.Hierarchical.Spectral.Utility
+
+-- | Get the components of a graphable object, an adjacency matrix.
+getComponentMats :: (Graphable a) => a -> [a]
+getComponentMats mat = fmap (fromGraph . flip G.subgraph gr) . G.components $ gr
+  where
+    gr = toGraph mat
+
+-- | Get the components of a graphable object, an adjacency matrix with the
+-- associated items.
+getComponentMatsItems :: (Graphable b) => V.Vector a -> b -> [(V.Vector a, b)]
+getComponentMatsItems items mat =
+    fmap (\ !xs -> (subsetVector items . sort $ xs, fromGraph . G.subgraph xs $ gr))
+      . G.components
+      $ gr
+  where
+    gr = toGraph mat
diff --git a/src/Math/Graph/Types.hs b/src/Math/Graph/Types.hs
new file mode 100644
--- /dev/null
+++ b/src/Math/Graph/Types.hs
@@ -0,0 +1,71 @@
+{- Math.Graph.Types
+Gregory W. Schwartz
+
+Types used for graph sections of the program.
+-}
+
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
+
+module Math.Graph.Types where
+
+-- Remote
+import Data.List (sort)
+import qualified Data.Eigen.SparseMatrix as E
+import qualified Data.Map.Strict as Map
+import qualified Data.Graph.Inductive as G
+import qualified Data.Sparse.Common as S
+import qualified Data.Vector.Unboxed as V
+import qualified Math.Clustering.Spectral.Dense as D
+import qualified Numeric.LinearAlgebra as H
+import qualified Numeric.LinearAlgebra.Sparse as S
+
+-- Local
+import qualified Math.Clustering.Spectral.Dense as D
+import qualified Math.Clustering.Spectral.Eigen.AdjacencyMatrix as E
+import qualified Math.Clustering.Spectral.Sparse as S
+
+-- | Get a re-mapped edge list with nodes ordered from 0 to the number of nodes
+-- in the graph.
+orderedEdges :: G.Gr Int a -> [(Int, Int, a)]
+orderedEdges gr =
+    fmap (\(!i,  !j,  !v) -> (getUpdate i, getUpdate j, v)) . G.labEdges $ gr
+  where
+    nodeMap = Map.fromList . flip zip [0..] . sort . G.nodes $ gr
+    getUpdate = flip ( Map.findWithDefault
+                        (error "Unexpected missing node in orderedEdges.")
+                     )
+                     nodeMap
+
+-- | Graphable class for converting matrices to and from a graph.
+class Graphable a where
+  toGraph :: a -> G.Gr Int Double
+  fromGraph :: G.Gr Int Double -> a
+
+instance Graphable D.AdjacencyMatrix where
+  toGraph mat = G.mkGraph (zip [0 .. H.rows mat - 1] [0 .. H.rows mat - 1])
+              . filter (\(_, _, x) -> x /= 0)
+              . concatMap (\(!i, !xs) -> fmap (\(!j, !v) -> (i, j, v)) xs)
+              . zip [0..]
+              . fmap (zip [0..] . H.toList)
+              . H.toRows
+              $ mat
+  fromGraph gr = H.assoc (G.noNodes gr, G.noNodes gr) 0
+               . fmap (\(!i, !j, !v) -> ((i, j), v))
+               . orderedEdges
+               $ gr
+
+instance Graphable S.AdjacencyMatrix where
+  toGraph mat = G.mkGraph (zip [0 .. S.nrows mat - 1] [0 .. S.nrows mat - 1])
+              . filter (\(_, _, x) -> x /= 0)
+              . S.toListSM
+              $ mat
+  fromGraph gr = S.fromListSM (G.noNodes gr, G.noNodes gr) . orderedEdges $ gr
+
+instance Graphable E.AdjacencyMatrix where
+  toGraph mat = G.mkGraph (zip [0 .. E.rows mat - 1] [0 .. E.rows mat - 1])
+              . filter (\(_, _, x) -> x /= 0)
+              . E.toList
+              $ mat
+  fromGraph gr = E.fromList (G.noNodes gr) (G.noNodes gr) . orderedEdges $ gr
