goal-simulation-0.1: scripts/markov-chain.hs

{-# LANGUAGE Arrows #-}

--- Imports ---


-- Goal --

import Goal.Core
import Goal.Geometry
import Goal.Simulation

import Goal.Probability

--- Main ---


main :: IO ()
main = do
    let sz = 5
        nstps = 20
        ts = [1..] :: [Int]
        x0 = 1
        xs = [1..sz]
        smtx = fromList (markovTensor xs) . concat . replicate sz $ replicate sz (1/fromIntegral sz)

    chn <- runWithSystemRandom $ markovChain smtx x0

    let chainToRenderable ln = toRenderable . execEC $ do

           layout_y_axis . laxis_generate .= scaledIntAxis defaultIntAxis (0,sz + 1)

           plot . liftEC $ do
                   plot_lines_style .= solidLine 3 (opaque red)
                   plot_lines_title .= "Markov Chain"
                   plot_lines_values .= [ln]

    let mly = proc t -> do
            x <- chn -< ()
            stps <- chainWindow nstps -< (t,x)
            returnA -< chainToRenderable stps

    initGUI

    apst <- newAnimationPost 2 (Just 10)

    forkIO $ streamM_ mly (postRenderable apst) ts

    mainGUI