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| 1 | +#!/usr/bin/env python |
| 2 | +#-*-encoding:utf8-*- |
| 3 | + |
| 4 | +""" |
| 5 | +Demonstrate how to create an interactive histogram, in which bars |
| 6 | +are hidden or shown by cliking on legend markers. |
| 7 | +
|
| 8 | +The interactivity is encoded in ecmascript and inserted in the SVG code |
| 9 | +in a post-processing step. To render the image, open it in a web |
| 10 | +browser. SVG is supported in most web browsers used by Linux and OSX |
| 11 | +users. Windows IE9 supports SVG, but earlier versions do not. |
| 12 | +
|
| 13 | + |
| 14 | +
|
| 15 | +""" |
| 16 | + |
| 17 | +import numpy as np |
| 18 | +import matplotlib.pyplot as plt |
| 19 | +import xml.etree.ElementTree as ET |
| 20 | +from StringIO import StringIO |
| 21 | + |
| 22 | +plt.rcParams['svg.embed_char_paths'] = 'none' |
| 23 | + |
| 24 | +# Apparently, this `register_namespace` method works only with |
| 25 | +# python 2.7 and up and is necessary to avoid garbling the XML name |
| 26 | +# space with ns0. |
| 27 | +ET.register_namespace("","http://www.w3.org/2000/svg") |
| 28 | + |
| 29 | + |
| 30 | +def python2js(d): |
| 31 | + """Return a string representation of a python dictionary in |
| 32 | + ecmascript object syntax.""" |
| 33 | + |
| 34 | + objs = [] |
| 35 | + for key, value in d.items(): |
| 36 | + objs.append( key + ':' + str(value) ) |
| 37 | + |
| 38 | + return '{' + ', '.join(objs) + '}' |
| 39 | + |
| 40 | + |
| 41 | +# --- Create histogram, legend and title --- |
| 42 | +plt.figure() |
| 43 | +r = np.random.randn(100) |
| 44 | +r1 = r + 1 |
| 45 | +labels = ['Rabbits', 'Frogs'] |
| 46 | +H = plt.hist([r,r1], label=labels) |
| 47 | +containers = H[-1] |
| 48 | +leg = plt.legend(frameon=False) |
| 49 | +plt.title("""From a web browser, click on the legend |
| 50 | +marker to toggle the corresponding histogram.""") |
| 51 | + |
| 52 | + |
| 53 | +# --- Add ids to the svg objects we'll modify |
| 54 | + |
| 55 | +hist_patches = {} |
| 56 | +for ic, c in enumerate(containers): |
| 57 | + hist_patches['hist_%d'%ic] = [] |
| 58 | + for il, element in enumerate(c): |
| 59 | + element.set_gid('hist_%d_patch_%d'%(ic, il)) |
| 60 | + hist_patches['hist_%d'%ic].append('hist_%d_patch_%d'%(ic,il)) |
| 61 | + |
| 62 | +# Set ids for the legend patches |
| 63 | +for i, t in enumerate(leg.get_patches()): |
| 64 | + t.set_gid('leg_patch_%d'%i) |
| 65 | + |
| 66 | +# Save SVG in a fake file object. |
| 67 | +f = StringIO() |
| 68 | +plt.savefig(f, format="svg") |
| 69 | + |
| 70 | +# Create XML tree from the SVG file. |
| 71 | +tree, xmlid = ET.XMLID(f.getvalue()) |
| 72 | + |
| 73 | + |
| 74 | +# --- Add interactivity --- |
| 75 | + |
| 76 | +# Add attributes to the patch objects. |
| 77 | +for i, t in enumerate(leg.get_patches()): |
| 78 | + el = xmlid['leg_patch_%d'%i] |
| 79 | + el.set('cursor', 'pointer') |
| 80 | + el.set('opacity', '1.0') |
| 81 | + el.set('onclick', "toggle_element(evt, 'hist_%d')"%i) |
| 82 | + |
| 83 | +# Create script defining the function `toggle_element`. |
| 84 | +# We create a global variable `container` that stores the patches id |
| 85 | +# belonging to each histogram. Then a function "toggle_element" sets the |
| 86 | +# visibility attribute of all patches of each histogram and the opacity |
| 87 | +# of the marker itself. |
| 88 | + |
| 89 | +script = """ |
| 90 | +<script type="text/ecmascript"> |
| 91 | +<![CDATA[ |
| 92 | +var container = %s |
| 93 | +
|
| 94 | +function toggle_element(evt, element) { |
| 95 | +
|
| 96 | + var names = container[element] |
| 97 | + var el, state; |
| 98 | + |
| 99 | + state = evt.target.getAttribute("opacity") == 1.0 || |
| 100 | + evt.target.getAttribute("opacity") == null; |
| 101 | + |
| 102 | + if (state) { |
| 103 | + evt.target.setAttribute("opacity", 0.5); |
| 104 | + |
| 105 | + for (var i=0; i < names.length; i++) { |
| 106 | + el = document.getElementById(names[i]); |
| 107 | + el.setAttribute("visibility","hidden"); |
| 108 | + } |
| 109 | + } |
| 110 | + |
| 111 | + else { |
| 112 | + evt.target.setAttribute("opacity", 1); |
| 113 | + |
| 114 | + for (var i=0; i < names.length; i++) { |
| 115 | + el = document.getElementById(names[i]); |
| 116 | + el.setAttribute("visibility","visible"); |
| 117 | + } |
| 118 | + |
| 119 | + }; |
| 120 | + }; |
| 121 | +]]> |
| 122 | +</script> |
| 123 | +"""%python2js(hist_patches) |
| 124 | + |
| 125 | +# Insert the script and save to file. |
| 126 | +tree.insert(0, ET.XML(script)) |
| 127 | + |
| 128 | +ET.ElementTree(tree).write("svg_histogram.svg") |
| 129 | + |
| 130 | + |
| 131 | + |
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