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import random
from pyx import *
# introduce a new symbol style where size and color are given by some data
class changesymbol(graph.style.symbol):
def __init__(self, sizecolumnname="size", colorcolumnname="color",
gradient=color.gradient.Rainbow,
symbol=graph.style.symbol.circle,
symbolattrs=[deco.filled, deco.stroked([color.gray.black])],
**kwargs):
# add some configuration parameters and modify some other
self.sizecolumnname = sizecolumnname
self.colorcolumnname = colorcolumnname
self.gradient = gradient
graph.style.symbol.__init__(self, symbol=symbol, symbolattrs=symbolattrs, **kwargs)
def columnnames(self, privatedata, sharedata, agraph, columnnames, dataaxisnames):
# register the new column names
if self.sizecolumnname not in columnnames:
raise ValueError("column '%s' missing" % self.sizecolumnname)
if self.colorcolumnname not in columnnames:
raise ValueError("column '%s' missing" % self.colorcolumnname)
return ([self.sizecolumnname, self.colorcolumnname] +
graph.style.symbol.columnnames(self, privatedata, sharedata, agraph,
columnnames, dataaxisnames))
def drawpoint(self, privatedata, sharedata, graph, point):
# replace the original drawpoint method by a slightly revised one
if sharedata.vposvalid and privatedata.symbolattrs is not None:
x_pt, y_pt = graph.vpos_pt(*sharedata.vpos)
color = self.gradient.getcolor(point[self.colorcolumnname])
privatedata.symbol(privatedata.symbolcanvas, x_pt, y_pt,
privatedata.size_pt*point[self.sizecolumnname],
privatedata.symbolattrs + [color])
g = graph.graphxy(width=10)
g.plot(graph.data.points([[random.random() for i in range(4)]
for i in range(1000)],
x=1, y=2, size=3, color=4),
[changesymbol()])
g.writeEPSfile("changesymbol")
g.writePDFfile("changesymbol")
g.writeSVGfile("changesymbol")
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