
Some of the things that increase the complexity of the chart library are:
- strongly typed axes (the library would be somewhat simpler if all axes were just doubles)
- achieving a balance between useful defaults and flexibility
- constraints between distinct visual elements
- the lack of “first class" text handling in the current diagrams library
I’ll follow your experiments with interest.
Tim
On 5 May 2014, at 3:58 am, Kai Zhang
Hi Tim,
Thank you for commenting. As I said before, Chart is a wonderful library. Although it has most features we need, I personally feel that it's cumbersome to make plots or define new plots by Chart. So I would like to experiment a new library which makes this process more natural and intuitive. For example, to make a plot, we can
1. generate axes from data by calling:
xAxis = realAxis rangeOfX padding opts yAxis = realAxis rangeOfY padding opts
2. Assemble axes:
area = plotArea 5.5 4.8 ( yAxis -- left axis , def -- top axis, using default axis which is a line , def -- right axis , xAxis -- bottom axis )
3. make delayed plots which are functions. Given a point map provided by plot area, they can generate actual plots.
ps = points xs ys def l = line xs ys def
3. attach any number and any types of plots to plot area:
plot = area <+ (ps, BL) <+ (l, BL)
We have four axes in plot area, so you can attach plots to plot area by any two of the axes, for example, you can do
area <+ (ps, BR) <+ (l, BL) <+ (l, TL) <+ (l, TR)
Each intermediate step can be easily customized separately and independently without worrying about other parts. And styling can be done by calling APIs of Diagrams.
On Sun, May 4, 2014 at 4:10 AM, Tim Docker
wrote: On 3 May 2014, at 7:44 am, Kai Zhang
wrote: 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))