Saving 'svg_filter_pie.svg'

importioimportxml.etree.ElementTreeasETimportmatplotlib.pyplotaspltfrommatplotlib.patchesimportShadow# make a square figure and Axesfig=plt.figure(figsize=(6,6))ax=fig.add_axes((0.1,0.1,0.8,0.8))labels='Frogs','Hogs','Dogs','Logs'fracs=[15,30,45,10]explode=(0,0.05,0,0)# We want to draw the shadow for each pie, but we will not use "shadow"# option as it doesn't save the references to the shadow patches.pie=ax.pie(fracs,explode=explode,labels=labels,autopct='%1.1f%%')forwinpie.wedges:# set the id with the label.w.set_gid(w.get_label())# we don't want to draw the edge of the piew.set_edgecolor("none")forwinpie.wedges:# create shadow patchs=Shadow(w,-0.01,-0.01)s.set_gid(w.get_gid()+"_shadow")s.set_zorder(w.get_zorder()-0.1)ax.add_patch(s)# savef=io.BytesIO()plt.savefig(f,format="svg")# Filter definition for shadow using a gaussian blur and lighting effect.# The lighting filter is copied from http://www.w3.org/TR/SVG/filters.html# I tested it with Inkscape and Firefox3. "Gaussian blur" is supported# in both, but the lighting effect only in Inkscape. Also note# that, Inkscape's exporting also may not support it.filter_def="""  <defs xmlns='http://www.w3.org/2000/svg'        xmlns:xlink='http://www.w3.org/1999/xlink'>    <filter id='dropshadow' height='1.2' width='1.2'>      <feGaussianBlur result='blur' stdDeviation='2'/>    </filter>    <filter id='MyFilter' filterUnits='objectBoundingBox'            x='0' y='0' width='1' height='1'>      <feGaussianBlur in='SourceAlpha' stdDeviation='4%' result='blur'/>      <feOffset in='blur' dx='4%' dy='4%' result='offsetBlur'/>      <feSpecularLighting in='blur' surfaceScale='5' specularConstant='.75'           specularExponent='20' lighting-color='#bbbbbb' result='specOut'>        <fePointLight x='-5000%' y='-10000%' z='20000%'/>      </feSpecularLighting>      <feComposite in='specOut' in2='SourceAlpha'                   operator='in' result='specOut'/>      <feComposite in='SourceGraphic' in2='specOut' operator='arithmetic'    k1='0' k2='1' k3='1' k4='0'/>    </filter>  </defs>"""tree,xmlid=ET.XMLID(f.getvalue())# insert the filter definition in the svg dom tree.tree.insert(0,ET.XML(filter_def))fori,pie_nameinenumerate(labels):pie=xmlid[pie_name]pie.set("filter",'url(#MyFilter)')shadow=xmlid[pie_name+"_shadow"]shadow.set("filter",'url(#dropshadow)')fn="svg_filter_pie.svg"print(f"Saving '{fn}'")ET.ElementTree(tree).write(fn)

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