examples/graphstyles/changesymbol.py

   1 import random
   2 from pyx import *
   3
   4 # introduce a new symbol style where size and color are given by some data
   5 class changesymbol(graph.style.symbol):
   6
   7     def __init__(self, sizecolumnname="size", colorcolumnname="color",
   8                        gradient=color.gradient.Rainbow,
   9                        symbol=graph.style.symbol.circle,
  10                        symbolattrs=[deco.filled, deco.stroked([color.gray.black])],
  11                        **kwargs):
  12         # add some configuration parameters and modify some other
  13         self.sizecolumnname = sizecolumnname
  14         self.colorcolumnname = colorcolumnname
  15         self.gradient = gradient
  16         graph.style.symbol.__init__(self, symbol=symbol, symbolattrs=symbolattrs, **kwargs)
  17
  18     def columnnames(self, privatedata, sharedata, agraph, columnnames, dataaxisnames):
  19         # register the new column names
  20         if self.sizecolumnname not in columnnames:
  21             raise ValueError("column '%s' missing" % self.sizecolumnname)
  22         if self.colorcolumnname not in columnnames:
  23             raise ValueError("column '%s' missing" % self.colorcolumnname)
  24         return ([self.sizecolumnname, self.colorcolumnname] +
  25                 graph.style.symbol.columnnames(self, privatedata, sharedata, agraph,
  26                                                columnnames, dataaxisnames))
  27
  28     def drawpoint(self, privatedata, sharedata, graph, point):
  29         # replace the original drawpoint method by a slightly revised one
  30         if sharedata.vposvalid and privatedata.symbolattrs is not None:
  31             x_pt, y_pt = graph.vpos_pt(*sharedata.vpos)
  32             color = self.gradient.getcolor(point[self.colorcolumnname])
  33             privatedata.symbol(privatedata.symbolcanvas, x_pt, y_pt,
  34                                privatedata.size_pt*point[self.sizecolumnname],
  35                                privatedata.symbolattrs + [color])
  36
  37 g = graph.graphxy(width=10)
  38 g.plot(graph.data.points([[random.random() for i in range(4)]
  39                           for i in range(1000)],
  40                          x=1, y=2, size=3, color=4),
  41        [changesymbol()])
  42 g.writeEPSfile("changesymbol")
  43 g.writePDFfile("changesymbol")