On 3 May 2014, at 7:44 am, Kai Zhang
1. There is few plotting library written in pure Haskell 2. Haskell-chart, one of the most featured library, is hard to extend and there is no straightforward way to compose or modify the plots generated by this library.
The chart library is pure haskell when using the diagrams backend. What do you mean by compose or modify the plots? It’s reasonably straightforward to have it produce a diagram, which can then be composed or modified with any of the diagrams tools. Some sample code is shown below. Tim (chart library maintainer) {-# LANGUAGE FlexibleContexts #-} import Graphics.Rendering.Chart import Data.Colour import Data.Colour.Names import Data.Colour.SRGB import Control.Lens import Data.Default.Class import Graphics.Rendering.Chart.Backend.Diagrams import qualified Diagrams.Prelude as D import qualified Diagrams.Backend.SVG as D chart :: Renderable (LayoutPick Double Double Double) chart = layoutToRenderable $ layout_title .~ "Amplitude Modulation" $ layout_plots .~ [toPlot sinusoid1] $ layout_plot_background .~ Just (solidFillStyle $ opaque white) $ def where am x = (sin (x*pi/45) + 1) / 2 * (sin (x*pi/5)) sinusoid1 = plot_lines_values .~ [[ (x,(am x)) | x <- [0,(0.5)..400]]] $ plot_lines_style .~ solidLine 1 (opaque blue) $ plot_lines_title .~"am" $ def mkDiagram :: (D.Backend b D.R2, D.Renderable (D.Path D.R2) b) => IO (D.Diagram b D.R2) mkDiagram = do env <- defaultEnv vectorAlignmentFns 800 400 return (fst (runBackendR env chart))