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haskellhaskell-chart

Human readable numbers with Haskell Charts

I'm trying to use Haskell-Charts (http://hackage.haskell.org/package/Chart) to generate some graphs. It works fine and I get a nice graph enter image description here

My only "problem" are the numbers on the left, that's a bit hard to read. Is there a way to maybe provide a function that would convert those numbers before displaying them ? I could convert the numbers before plotting, but I would lose precision. I've been looking at the doc but I don't see it, if it exists.

Thanks

EDIT : Here is the code.

import Graphics.Rendering.Chart.Easy
import Graphics.Rendering.Chart.Axis.LocalTime
import Graphics.Rendering.Chart.Backend.Diagrams
import Data.Time.LocalTime

main = do
  -- Get datas
  toFile def "test.svg" $ do
    layout_title .= "Active mem"
    plot (line "Active" $ [L.map (\v -> ((utcToLocalTime utc $ time v) :: LocalTime, (fromIntegral $ value v) :: Int)) $ V.toList q])

Unfortunately I get the data from a database, and I can't give public access to it. But a list of [(LocalTime, Int)] with big numbers should give you something similar. I'm using the Diagrams backend btw

Solution

  • Digging into the source of the Chart, maybe I found the solution.

    Here's working code. you can change func to anything you like

    This will show label of y-axis 10,20,30,40, when actual data is 100,200,300,400

    import Graphics.Rendering.Chart.Easy
import Graphics.Rendering.Chart.Backend.Diagrams

func :: Int -> String
func x = show $ x `quot` 10

vals :: [(Int,Int)]
vals = [(1,100),(2,200),(3,300),(4,400)]
main = do
  toFile def "test.svg" $ do
    layout_title .= "test"
    layout_y_axis . laxis_generate .= autoScaledIntAxis(LinearAxisParams{
        _la_labelf = map func,
        _la_nLabels = 5,
        _la_nTicks = 10
        })
    plot $ points "Score" vals