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{-# LANGUAGE TemplateHaskell, FlexibleInstances #-}
module Graphics.Rendering.Chart.Plot.Histogram
( -- * Histograms
PlotHist (..)
, histToPlot
, defaultPlotHist
, defaultFloatPlotHist
, defaultNormedPlotHist
, histToBins
-- * Accessors
, plot_hist_title
, plot_hist_bins
, plot_hist_values
, plot_hist_no_zeros
, plot_hist_range
, plot_hist_drop_lines
, plot_hist_line_style
, plot_hist_fill_style
, plot_hist_norm_func
) where
import Control.Monad (when)
import Data.Maybe (fromMaybe)
import qualified Data.Foldable as F
import qualified Data.Vector as V
import Control.Lens
import Graphics.Rendering.Chart.Plot.Types
import Graphics.Rendering.Chart.Geometry
import Graphics.Rendering.Chart.Drawing
import Data.Default.Class
import Data.Colour (opaque)
import Data.Colour.Names (blue)
import Data.Colour.SRGB (sRGB)
import Numeric.Histogram
data PlotHist x y = PlotHist
{ -- | Plot title
_plot_hist_title :: String
-- | Number of bins
, _plot_hist_bins :: Int
-- | Values to histogram
, _plot_hist_values :: [x]
-- | Don't attempt to plot bins with zero counts. Useful when
-- the y-axis is logarithmically scaled.
, _plot_hist_no_zeros :: Bool
-- | Override the range of the histogram. If @Nothing@ the
-- range of @_plot_hist_values@ is used.
--
-- Note that any normalization is always computed over the full
-- data set, including samples not falling in the histogram range.
, _plot_hist_range :: Maybe (x,x)
-- | Plot vertical lines between bins
, _plot_hist_drop_lines :: Bool
-- | Fill style of the bins
, _plot_hist_fill_style :: FillStyle
-- | Line style of the bin outlines
, _plot_hist_line_style :: LineStyle
-- | Normalization function
, _plot_hist_norm_func :: Double -> Int -> y
}
instance Default (PlotHist x Int) where
def = defaultPlotHist
-- | The default style is an unnormalized histogram of 20 bins.
defaultPlotHist :: PlotHist x Int
defaultPlotHist = PlotHist { _plot_hist_bins = 20
, _plot_hist_title = ""
, _plot_hist_values = []
, _plot_hist_no_zeros = False
, _plot_hist_range = Nothing
, _plot_hist_drop_lines = False
, _plot_hist_line_style = defaultLineStyle
, _plot_hist_fill_style = defaultFillStyle
, _plot_hist_norm_func = const id
}
-- | @defaultPlotHist@ but with real counts
defaultFloatPlotHist :: PlotHist x Double
defaultFloatPlotHist = defaultPlotHist { _plot_hist_norm_func = const realToFrac }
-- | @defaultPlotHist@ but normalized such that the integral of the
-- histogram is one.
defaultNormedPlotHist :: PlotHist x Double
defaultNormedPlotHist = defaultPlotHist { _plot_hist_norm_func = \n y->realToFrac y / n }
defaultFillStyle :: FillStyle
defaultFillStyle = solidFillStyle (opaque $ sRGB 0.5 0.5 1.0)
defaultLineStyle :: LineStyle
defaultLineStyle = (solidLine 1 $ opaque blue)
{ _line_cap = LineCapButt
, _line_join = LineJoinMiter
}
-- | Convert a @PlotHist@ to a @Plot@
--
-- N.B. In principle this should be Chart's @ToPlot@ class but unfortunately
-- this does not allow us to set bounds on the x and y axis types, hence
-- the need for this function.
histToPlot :: (RealFrac x, Num y, Ord y) => PlotHist x y -> Plot x y
histToPlot p = Plot {
_plot_render = renderPlotHist p,
_plot_legend = [(_plot_hist_title p, renderPlotLegendHist p)],
_plot_all_points = unzip
$ concatMap (\((x1,x2), y)->[ (x1,y)
, (x2,y)
, (x1,0)
, (x2,0)
])
$ histToBins p
}
buildHistPath :: (RealFrac x, Num y)
=> PointMapFn x y -> [((x,x), y)] -> Path
buildHistPath _ [] = End
buildHistPath pmap bins = MoveTo (pt xb 0) (go bins)
where go [((x1,x2),y)] = LineTo (pt x1 y)
$ LineTo (pt x2 y)
$ LineTo (pt x2 0)
$ End
go (((x1,x2),y):rest) = LineTo (pt x1 y)
$ LineTo (pt x2 y)
$ go rest
go [] = End
((xb,_),_) = head bins
pt x y = pmap (LValue x, LValue y)
renderPlotHist :: (RealFrac x, Num y, Ord y)
=> PlotHist x y -> PointMapFn x y -> BackendProgram ()
renderPlotHist p pmap
| null bins = return ()
| otherwise = do
withFillStyle (_plot_hist_fill_style p) $
alignFillPath (buildHistPath pmap bins) >>= fillPath
withLineStyle (_plot_hist_line_style p) $ do
when (_plot_hist_drop_lines p) $
alignStrokePath dropLinesPath >>= strokePath
alignStrokePath (buildHistPath pmap bins) >>= strokePath
where bins = histToBins p
pt x y = pmap (LValue x, LValue y)
dropLinesPath = F.foldMap (\((x1,_), y)->moveTo (pt x1 0)
<> lineTo (pt x1 y)
) $ tail bins
renderPlotLegendHist :: PlotHist x y -> Rect -> BackendProgram ()
renderPlotLegendHist p (Rect p1 p2) =
withLineStyle (_plot_hist_line_style p) $
let y = (p_y p1 + p_y p2) / 2
in strokePath $ moveTo' (p_x p1) y <> lineTo' (p_x p2) y
-- | Obtain the bin dimensions of a given @PlotHist@.
histToBins :: (RealFrac x, Num y, Ord y) => PlotHist x y -> [((x,x), y)]
histToBins hist =
filter_zeros $ zip bounds $ counts
where n = _plot_hist_bins hist
(a,b) = realHistRange hist
dx = realToFrac (b-a) / realToFrac n
bounds = binBounds a b n
values = V.fromList (_plot_hist_values hist)
filter_zeros | _plot_hist_no_zeros hist = filter (\(_,c)->c > 0)
| otherwise = id
norm = dx * realToFrac (V.length values)
normalize = _plot_hist_norm_func hist norm
counts = V.toList $ V.map (normalize . snd)
$ histWithBins (V.fromList bounds)
$ zip (repeat 1) (V.toList values)
realHistRange :: (RealFrac x) => PlotHist x y -> (x,x)
realHistRange hist = fromMaybe range $ _plot_hist_range hist
where values = V.fromList (_plot_hist_values hist)
range = if V.null values
then (0,0)
else (V.minimum values, V.maximum values)
$( makeLenses ''PlotHist )
|
