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<div class="section" id="api-example-code-custom-projection-example-py">
<span id="api-custom-projection-example"></span><h1>api example code: custom_projection_example.py<a class="headerlink" href="#api-example-code-custom-projection-example-py" title="Permalink to this headline">ΒΆ</a></h1>
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<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">matplotlib.axes</span> <span class="kn">import</span> <span class="n">Axes</span>
<span class="kn">from</span> <span class="nn">matplotlib</span> <span class="kn">import</span> <span class="n">cbook</span>
<span class="kn">from</span> <span class="nn">matplotlib.patches</span> <span class="kn">import</span> <span class="n">Circle</span>
<span class="kn">from</span> <span class="nn">matplotlib.path</span> <span class="kn">import</span> <span class="n">Path</span>
<span class="kn">from</span> <span class="nn">matplotlib.ticker</span> <span class="kn">import</span> <span class="n">Formatter</span><span class="p">,</span> <span class="n">Locator</span><span class="p">,</span> <span class="n">NullLocator</span><span class="p">,</span> <span class="n">FixedLocator</span><span class="p">,</span> <span class="n">NullFormatter</span>
<span class="kn">from</span> <span class="nn">matplotlib.transforms</span> <span class="kn">import</span> <span class="n">Affine2D</span><span class="p">,</span> <span class="n">Affine2DBase</span><span class="p">,</span> <span class="n">Bbox</span><span class="p">,</span> \
<span class="n">BboxTransformTo</span><span class="p">,</span> <span class="n">IdentityTransform</span><span class="p">,</span> <span class="n">Transform</span><span class="p">,</span> <span class="n">TransformWrapper</span>
<span class="kn">from</span> <span class="nn">matplotlib.projections</span> <span class="kn">import</span> <span class="n">register_projection</span>
<span class="kn">import</span> <span class="nn">matplotlib.spines</span> <span class="kn">as</span> <span class="nn">mspines</span>
<span class="kn">import</span> <span class="nn">matplotlib.axis</span> <span class="kn">as</span> <span class="nn">maxis</span>
<span class="kn">import</span> <span class="nn">numpy</span> <span class="kn">as</span> <span class="nn">np</span>
<span class="c"># This example projection class is rather long, but it is designed to</span>
<span class="c"># illustrate many features, not all of which will be used every time.</span>
<span class="c"># It is also common to factor out a lot of these methods into common</span>
<span class="c"># code used by a number of projections with similar characteristics</span>
<span class="c"># (see geo.py).</span>
<span class="k">class</span> <span class="nc">HammerAxes</span><span class="p">(</span><span class="n">Axes</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> A custom class for the Aitoff-Hammer projection, an equal-area map</span>
<span class="sd"> projection.</span>
<span class="sd"> http://en.wikipedia.org/wiki/Hammer_projection</span>
<span class="sd"> """</span>
<span class="c"># The projection must specify a name. This will be used be the</span>
<span class="c"># user to select the projection, i.e. ``subplot(111,</span>
<span class="c"># projection='custom_hammer')``.</span>
<span class="n">name</span> <span class="o">=</span> <span class="s">'custom_hammer'</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">set_aspect</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="n">adjustable</span><span class="o">=</span><span class="s">'box'</span><span class="p">,</span> <span class="n">anchor</span><span class="o">=</span><span class="s">'C'</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">cla</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">_init_axis</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">xaxis</span> <span class="o">=</span> <span class="n">maxis</span><span class="o">.</span><span class="n">XAxis</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">yaxis</span> <span class="o">=</span> <span class="n">maxis</span><span class="o">.</span><span class="n">YAxis</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="c"># Do not register xaxis or yaxis with spines -- as done in</span>
<span class="c"># Axes._init_axis() -- until HammerAxes.xaxis.cla() works.</span>
<span class="c"># self.spines['hammer'].register_axis(self.yaxis)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_update_transScale</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">cla</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override to set up some reasonable defaults.</span>
<span class="sd"> """</span>
<span class="c"># Don't forget to call the base class</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">cla</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="c"># Set up a default grid spacing</span>
<span class="bp">self</span><span class="o">.</span><span class="n">set_longitude_grid</span><span class="p">(</span><span class="mi">30</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">set_latitude_grid</span><span class="p">(</span><span class="mi">15</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">set_longitude_grid_ends</span><span class="p">(</span><span class="mi">75</span><span class="p">)</span>
<span class="c"># Turn off minor ticking altogether</span>
<span class="bp">self</span><span class="o">.</span><span class="n">xaxis</span><span class="o">.</span><span class="n">set_minor_locator</span><span class="p">(</span><span class="n">NullLocator</span><span class="p">())</span>
<span class="bp">self</span><span class="o">.</span><span class="n">yaxis</span><span class="o">.</span><span class="n">set_minor_locator</span><span class="p">(</span><span class="n">NullLocator</span><span class="p">())</span>
<span class="c"># Do not display ticks -- we only want gridlines and text</span>
<span class="bp">self</span><span class="o">.</span><span class="n">xaxis</span><span class="o">.</span><span class="n">set_ticks_position</span><span class="p">(</span><span class="s">'none'</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">yaxis</span><span class="o">.</span><span class="n">set_ticks_position</span><span class="p">(</span><span class="s">'none'</span><span class="p">)</span>
<span class="c"># The limits on this projection are fixed -- they are not to</span>
<span class="c"># be changed by the user. This makes the math in the</span>
<span class="c"># transformation itself easier, and since this is a toy</span>
<span class="c"># example, the easier, the better.</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_xlim</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_ylim</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_set_lim_and_transforms</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> This is called once when the plot is created to set up all the</span>
<span class="sd"> transforms for the data, text and grids.</span>
<span class="sd"> """</span>
<span class="c"># There are three important coordinate spaces going on here:</span>
<span class="c">#</span>
<span class="c"># 1. Data space: The space of the data itself</span>
<span class="c">#</span>
<span class="c"># 2. Axes space: The unit rectangle (0, 0) to (1, 1)</span>
<span class="c"># covering the entire plot area.</span>
<span class="c">#</span>
<span class="c"># 3. Display space: The coordinates of the resulting image,</span>
<span class="c"># often in pixels or dpi/inch.</span>
<span class="c"># This function makes heavy use of the Transform classes in</span>
<span class="c"># ``lib/matplotlib/transforms.py.`` For more information, see</span>
<span class="c"># the inline documentation there.</span>
<span class="c"># The goal of the first two transformations is to get from the</span>
<span class="c"># data space (in this case longitude and latitude) to axes</span>
<span class="c"># space. It is separated into a non-affine and affine part so</span>
<span class="c"># that the non-affine part does not have to be recomputed when</span>
<span class="c"># a simple affine change to the figure has been made (such as</span>
<span class="c"># resizing the window or changing the dpi).</span>
<span class="c"># 1) The core transformation from data space into</span>
<span class="c"># rectilinear space defined in the HammerTransform class.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">transProjection</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">HammerTransform</span><span class="p">()</span>
<span class="c"># 2) The above has an output range that is not in the unit</span>
<span class="c"># rectangle, so scale and translate it so it fits correctly</span>
<span class="c"># within the axes. The peculiar calculations of xscale and</span>
<span class="c"># yscale are specific to a Aitoff-Hammer projection, so don't</span>
<span class="c"># worry about them too much.</span>
<span class="n">xscale</span> <span class="o">=</span> <span class="mf">2.0</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">sqrt</span><span class="p">(</span><span class="mf">2.0</span><span class="p">)</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">sin</span><span class="p">(</span><span class="mf">0.5</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="n">yscale</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">sqrt</span><span class="p">(</span><span class="mf">2.0</span><span class="p">)</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">sin</span><span class="p">(</span><span class="mf">0.5</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">transAffine</span> <span class="o">=</span> <span class="n">Affine2D</span><span class="p">()</span> \
<span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">0.5</span> <span class="o">/</span> <span class="n">xscale</span><span class="p">,</span> <span class="mf">0.5</span> <span class="o">/</span> <span class="n">yscale</span><span class="p">)</span> \
<span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">)</span>
<span class="c"># 3) This is the transformation from axes space to display</span>
<span class="c"># space.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">transAxes</span> <span class="o">=</span> <span class="n">BboxTransformTo</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">bbox</span><span class="p">)</span>
<span class="c"># Now put these 3 transforms together -- from data all the way</span>
<span class="c"># to display coordinates. Using the '+' operator, these</span>
<span class="c"># transforms will be applied "in order". The transforms are</span>
<span class="c"># automatically simplified, if possible, by the underlying</span>
<span class="c"># transformation framework.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">transData</span> <span class="o">=</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transProjection</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transAffine</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transAxes</span>
<span class="c"># The main data transformation is set up. Now deal with</span>
<span class="c"># gridlines and tick labels.</span>
<span class="c"># Longitude gridlines and ticklabels. The input to these</span>
<span class="c"># transforms are in display space in x and axes space in y.</span>
<span class="c"># Therefore, the input values will be in range (-xmin, 0),</span>
<span class="c"># (xmax, 1). The goal of these transforms is to go from that</span>
<span class="c"># space to display space. The tick labels will be offset 4</span>
<span class="c"># pixels from the equator.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_pretransform</span> <span class="o">=</span> \
<span class="n">Affine2D</span><span class="p">()</span> \
<span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span> \
<span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_transform</span> <span class="o">=</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_pretransform</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transData</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_text1_transform</span> <span class="o">=</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transData</span> <span class="o">+</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="mf">4.0</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_text2_transform</span> <span class="o">=</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transData</span> <span class="o">+</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="mf">4.0</span><span class="p">)</span>
<span class="c"># Now set up the transforms for the latitude ticks. The input to</span>
<span class="c"># these transforms are in axes space in x and display space in</span>
<span class="c"># y. Therefore, the input values will be in range (0, -ymin),</span>
<span class="c"># (1, ymax). The goal of these transforms is to go from that</span>
<span class="c"># space to display space. The tick labels will be offset 4</span>
<span class="c"># pixels from the edge of the axes ellipse.</span>
<span class="n">yaxis_stretch</span> <span class="o">=</span> <span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">*</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">1.0</span><span class="p">)</span><span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="n">yaxis_space</span> <span class="o">=</span> <span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">1.1</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_transform</span> <span class="o">=</span> \
<span class="n">yaxis_stretch</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transData</span>
<span class="n">yaxis_text_base</span> <span class="o">=</span> \
<span class="n">yaxis_stretch</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transProjection</span> <span class="o">+</span> \
<span class="p">(</span><span class="n">yaxis_space</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transAffine</span> <span class="o">+</span> \
<span class="bp">self</span><span class="o">.</span><span class="n">transAxes</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_text1_transform</span> <span class="o">=</span> \
<span class="n">yaxis_text_base</span> <span class="o">+</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="o">-</span><span class="mf">8.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_text2_transform</span> <span class="o">=</span> \
<span class="n">yaxis_text_base</span> <span class="o">+</span> \
<span class="n">Affine2D</span><span class="p">()</span><span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">8.0</span><span class="p">,</span> <span class="mf">0.0</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">get_xaxis_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span><span class="n">which</span><span class="o">=</span><span class="s">'grid'</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> x-axis grid and ticks.</span>
<span class="sd"> """</span>
<span class="k">assert</span> <span class="n">which</span> <span class="ow">in</span> <span class="p">[</span><span class="s">'tick1'</span><span class="p">,</span><span class="s">'tick2'</span><span class="p">,</span><span class="s">'grid'</span><span class="p">]</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_transform</span>
<span class="k">def</span> <span class="nf">get_xaxis_text1_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pixelPad</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> x-axis tick labels.</span>
<span class="sd"> Returns a tuple of the form (transform, valign, halign)</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_text1_transform</span><span class="p">,</span> <span class="s">'bottom'</span><span class="p">,</span> <span class="s">'center'</span>
<span class="k">def</span> <span class="nf">get_xaxis_text2_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pixelPad</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> secondary x-axis tick labels.</span>
<span class="sd"> Returns a tuple of the form (transform, valign, halign)</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_text2_transform</span><span class="p">,</span> <span class="s">'top'</span><span class="p">,</span> <span class="s">'center'</span>
<span class="k">def</span> <span class="nf">get_yaxis_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span><span class="n">which</span><span class="o">=</span><span class="s">'grid'</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> y-axis grid and ticks.</span>
<span class="sd"> """</span>
<span class="k">assert</span> <span class="n">which</span> <span class="ow">in</span> <span class="p">[</span><span class="s">'tick1'</span><span class="p">,</span><span class="s">'tick2'</span><span class="p">,</span><span class="s">'grid'</span><span class="p">]</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_transform</span>
<span class="k">def</span> <span class="nf">get_yaxis_text1_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pixelPad</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> y-axis tick labels.</span>
<span class="sd"> Returns a tuple of the form (transform, valign, halign)</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_text1_transform</span><span class="p">,</span> <span class="s">'center'</span><span class="p">,</span> <span class="s">'right'</span>
<span class="k">def</span> <span class="nf">get_yaxis_text2_transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">pixelPad</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to provide a transformation for the</span>
<span class="sd"> secondary y-axis tick labels.</span>
<span class="sd"> Returns a tuple of the form (transform, valign, halign)</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_yaxis_text2_transform</span><span class="p">,</span> <span class="s">'center'</span><span class="p">,</span> <span class="s">'left'</span>
<span class="k">def</span> <span class="nf">_gen_axes_patch</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to define the shape that is used for the</span>
<span class="sd"> background of the plot. It should be a subclass of Patch.</span>
<span class="sd"> In this case, it is a Circle (that may be warped by the axes</span>
<span class="sd"> transform into an ellipse). Any data and gridlines will be</span>
<span class="sd"> clipped to this shape.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="n">Circle</span><span class="p">((</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">),</span> <span class="mf">0.5</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_gen_axes_spines</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="p">{</span><span class="s">'custom_hammer'</span><span class="p">:</span><span class="n">mspines</span><span class="o">.</span><span class="n">Spine</span><span class="o">.</span><span class="n">circular_spine</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span>
<span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">),</span> <span class="mf">0.5</span><span class="p">)}</span>
<span class="c"># Prevent the user from applying scales to one or both of the</span>
<span class="c"># axes. In this particular case, scaling the axes wouldn't make</span>
<span class="c"># sense, so we don't allow it.</span>
<span class="k">def</span> <span class="nf">set_xscale</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">if</span> <span class="n">args</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">!=</span> <span class="s">'linear'</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">NotImplementedError</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_xscale</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">set_yscale</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">if</span> <span class="n">args</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">!=</span> <span class="s">'linear'</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">NotImplementedError</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_yscale</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="c"># Prevent the user from changing the axes limits. In our case, we</span>
<span class="c"># want to display the whole sphere all the time, so we override</span>
<span class="c"># set_xlim and set_ylim to ignore any input. This also applies to</span>
<span class="c"># interactive panning and zooming in the GUI interfaces.</span>
<span class="k">def</span> <span class="nf">set_xlim</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_xlim</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="n">Axes</span><span class="o">.</span><span class="n">set_ylim</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">)</span>
<span class="n">set_ylim</span> <span class="o">=</span> <span class="n">set_xlim</span>
<span class="k">def</span> <span class="nf">format_coord</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">long</span><span class="p">,</span> <span class="n">lat</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override this method to change how the values are displayed in</span>
<span class="sd"> the status bar.</span>
<span class="sd"> In this case, we want them to be displayed in degrees N/S/E/W.</span>
<span class="sd"> """</span>
<span class="nb">long</span> <span class="o">=</span> <span class="nb">long</span> <span class="o">*</span> <span class="p">(</span><span class="mf">180.0</span> <span class="o">/</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="n">lat</span> <span class="o">=</span> <span class="n">lat</span> <span class="o">*</span> <span class="p">(</span><span class="mf">180.0</span> <span class="o">/</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span>
<span class="k">if</span> <span class="n">lat</span> <span class="o">>=</span> <span class="mf">0.0</span><span class="p">:</span>
<span class="n">ns</span> <span class="o">=</span> <span class="s">'N'</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">ns</span> <span class="o">=</span> <span class="s">'S'</span>
<span class="k">if</span> <span class="nb">long</span> <span class="o">>=</span> <span class="mf">0.0</span><span class="p">:</span>
<span class="n">ew</span> <span class="o">=</span> <span class="s">'E'</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">ew</span> <span class="o">=</span> <span class="s">'W'</span>
<span class="c"># \u00b0 : degree symbol</span>
<span class="k">return</span> <span class="s">u'</span><span class="si">%f</span><span class="se">\u00b0</span><span class="si">%s</span><span class="s">, </span><span class="si">%f</span><span class="se">\u00b0</span><span class="si">%s</span><span class="s">'</span> <span class="o">%</span> <span class="p">(</span><span class="nb">abs</span><span class="p">(</span><span class="n">lat</span><span class="p">),</span> <span class="n">ns</span><span class="p">,</span> <span class="nb">abs</span><span class="p">(</span><span class="nb">long</span><span class="p">),</span> <span class="n">ew</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">DegreeFormatter</span><span class="p">(</span><span class="n">Formatter</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> This is a custom formatter that converts the native unit of</span>
<span class="sd"> radians into (truncated) degrees and adds a degree symbol.</span>
<span class="sd"> """</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">round_to</span><span class="o">=</span><span class="mf">1.0</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_round_to</span> <span class="o">=</span> <span class="n">round_to</span>
<span class="k">def</span> <span class="nf">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">pos</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="n">degrees</span> <span class="o">=</span> <span class="p">(</span><span class="n">x</span> <span class="o">/</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">)</span> <span class="o">*</span> <span class="mf">180.0</span>
<span class="n">degrees</span> <span class="o">=</span> <span class="nb">round</span><span class="p">(</span><span class="n">degrees</span> <span class="o">/</span> <span class="bp">self</span><span class="o">.</span><span class="n">_round_to</span><span class="p">)</span> <span class="o">*</span> <span class="bp">self</span><span class="o">.</span><span class="n">_round_to</span>
<span class="c"># \u00b0 : degree symbol</span>
<span class="k">return</span> <span class="s">u"</span><span class="si">%d</span><span class="se">\u00b0</span><span class="s">"</span> <span class="o">%</span> <span class="n">degrees</span>
<span class="k">def</span> <span class="nf">set_longitude_grid</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">degrees</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Set the number of degrees between each longitude grid.</span>
<span class="sd"> This is an example method that is specific to this projection</span>
<span class="sd"> class -- it provides a more convenient interface to set the</span>
<span class="sd"> ticking than set_xticks would.</span>
<span class="sd"> """</span>
<span class="c"># Set up a FixedLocator at each of the points, evenly spaced</span>
<span class="c"># by degrees.</span>
<span class="n">number</span> <span class="o">=</span> <span class="p">(</span><span class="mf">360.0</span> <span class="o">/</span> <span class="n">degrees</span><span class="p">)</span> <span class="o">+</span> <span class="mi">1</span>
<span class="bp">self</span><span class="o">.</span><span class="n">xaxis</span><span class="o">.</span><span class="n">set_major_locator</span><span class="p">(</span>
<span class="n">FixedLocator</span><span class="p">(</span>
<span class="n">np</span><span class="o">.</span><span class="n">linspace</span><span class="p">(</span><span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span><span class="p">,</span> <span class="n">number</span><span class="p">,</span> <span class="bp">True</span><span class="p">)[</span><span class="mi">1</span><span class="p">:</span><span class="o">-</span><span class="mi">1</span><span class="p">]))</span>
<span class="c"># Set the formatter to display the tick labels in degrees,</span>
<span class="c"># rather than radians.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">xaxis</span><span class="o">.</span><span class="n">set_major_formatter</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">DegreeFormatter</span><span class="p">(</span><span class="n">degrees</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">set_latitude_grid</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">degrees</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Set the number of degrees between each longitude grid.</span>
<span class="sd"> This is an example method that is specific to this projection</span>
<span class="sd"> class -- it provides a more convenient interface than</span>
<span class="sd"> set_yticks would.</span>
<span class="sd"> """</span>
<span class="c"># Set up a FixedLocator at each of the points, evenly spaced</span>
<span class="c"># by degrees.</span>
<span class="n">number</span> <span class="o">=</span> <span class="p">(</span><span class="mf">180.0</span> <span class="o">/</span> <span class="n">degrees</span><span class="p">)</span> <span class="o">+</span> <span class="mi">1</span>
<span class="bp">self</span><span class="o">.</span><span class="n">yaxis</span><span class="o">.</span><span class="n">set_major_locator</span><span class="p">(</span>
<span class="n">FixedLocator</span><span class="p">(</span>
<span class="n">np</span><span class="o">.</span><span class="n">linspace</span><span class="p">(</span><span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">,</span> <span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">2.0</span><span class="p">,</span> <span class="n">number</span><span class="p">,</span> <span class="bp">True</span><span class="p">)[</span><span class="mi">1</span><span class="p">:</span><span class="o">-</span><span class="mi">1</span><span class="p">]))</span>
<span class="c"># Set the formatter to display the tick labels in degrees,</span>
<span class="c"># rather than radians.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">yaxis</span><span class="o">.</span><span class="n">set_major_formatter</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">DegreeFormatter</span><span class="p">(</span><span class="n">degrees</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">set_longitude_grid_ends</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">degrees</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Set the latitude(s) at which to stop drawing the longitude grids.</span>
<span class="sd"> Often, in geographic projections, you wouldn't want to draw</span>
<span class="sd"> longitude gridlines near the poles. This allows the user to</span>
<span class="sd"> specify the degree at which to stop drawing longitude grids.</span>
<span class="sd"> This is an example method that is specific to this projection</span>
<span class="sd"> class -- it provides an interface to something that has no</span>
<span class="sd"> analogy in the base Axes class.</span>
<span class="sd"> """</span>
<span class="n">longitude_cap</span> <span class="o">=</span> <span class="n">degrees</span> <span class="o">*</span> <span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">pi</span> <span class="o">/</span> <span class="mf">180.0</span><span class="p">)</span>
<span class="c"># Change the xaxis gridlines transform so that it draws from</span>
<span class="c"># -degrees to degrees, rather than -pi to pi.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_xaxis_pretransform</span> \
<span class="o">.</span><span class="n">clear</span><span class="p">()</span> \
<span class="o">.</span><span class="n">scale</span><span class="p">(</span><span class="mf">1.0</span><span class="p">,</span> <span class="n">longitude_cap</span> <span class="o">*</span> <span class="mf">2.0</span><span class="p">)</span> \
<span class="o">.</span><span class="n">translate</span><span class="p">(</span><span class="mf">0.0</span><span class="p">,</span> <span class="o">-</span><span class="n">longitude_cap</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">get_data_ratio</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Return the aspect ratio of the data itself.</span>
<span class="sd"> This method should be overridden by any Axes that have a</span>
<span class="sd"> fixed data ratio.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="mf">1.0</span>
<span class="c"># Interactive panning and zooming is not supported with this projection,</span>
<span class="c"># so we override all of the following methods to disable it.</span>
<span class="k">def</span> <span class="nf">can_zoom</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Return True if this axes support the zoom box</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="bp">False</span>
<span class="k">def</span> <span class="nf">start_pan</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="n">button</span><span class="p">):</span>
<span class="k">pass</span>
<span class="k">def</span> <span class="nf">end_pan</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">pass</span>
<span class="k">def</span> <span class="nf">drag_pan</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">button</span><span class="p">,</span> <span class="n">key</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">):</span>
<span class="k">pass</span>
<span class="c"># Now, the transforms themselves.</span>
<span class="k">class</span> <span class="nc">HammerTransform</span><span class="p">(</span><span class="n">Transform</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> The base Hammer transform.</span>
<span class="sd"> """</span>
<span class="n">input_dims</span> <span class="o">=</span> <span class="mi">2</span>
<span class="n">output_dims</span> <span class="o">=</span> <span class="mi">2</span>
<span class="n">is_separable</span> <span class="o">=</span> <span class="bp">False</span>
<span class="k">def</span> <span class="nf">transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">ll</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Override the transform method to implement the custom transform.</span>
<span class="sd"> The input and output are Nx2 numpy arrays.</span>
<span class="sd"> """</span>
<span class="n">longitude</span> <span class="o">=</span> <span class="n">ll</span><span class="p">[:,</span> <span class="mi">0</span><span class="p">:</span><span class="mi">1</span><span class="p">]</span>
<span class="n">latitude</span> <span class="o">=</span> <span class="n">ll</span><span class="p">[:,</span> <span class="mi">1</span><span class="p">:</span><span class="mi">2</span><span class="p">]</span>
<span class="c"># Pre-compute some values</span>
<span class="n">half_long</span> <span class="o">=</span> <span class="n">longitude</span> <span class="o">/</span> <span class="mf">2.0</span>
<span class="n">cos_latitude</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">cos</span><span class="p">(</span><span class="n">latitude</span><span class="p">)</span>
<span class="n">sqrt2</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">sqrt</span><span class="p">(</span><span class="mf">2.0</span><span class="p">)</span>
<span class="n">alpha</span> <span class="o">=</span> <span class="mf">1.0</span> <span class="o">+</span> <span class="n">cos_latitude</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">cos</span><span class="p">(</span><span class="n">half_long</span><span class="p">)</span>
<span class="n">x</span> <span class="o">=</span> <span class="p">(</span><span class="mf">2.0</span> <span class="o">*</span> <span class="n">sqrt2</span><span class="p">)</span> <span class="o">*</span> <span class="p">(</span><span class="n">cos_latitude</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">sin</span><span class="p">(</span><span class="n">half_long</span><span class="p">))</span> <span class="o">/</span> <span class="n">alpha</span>
<span class="n">y</span> <span class="o">=</span> <span class="p">(</span><span class="n">sqrt2</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">sin</span><span class="p">(</span><span class="n">latitude</span><span class="p">))</span> <span class="o">/</span> <span class="n">alpha</span>
<span class="k">return</span> <span class="n">np</span><span class="o">.</span><span class="n">concatenate</span><span class="p">((</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">),</span> <span class="mi">1</span><span class="p">)</span>
<span class="c"># This is where things get interesting. With this projection,</span>
<span class="c"># straight lines in data space become curves in display space.</span>
<span class="c"># This is done by interpolating new values between the input</span>
<span class="c"># values of the data. Since ``transform`` must not return a</span>
<span class="c"># differently-sized array, any transform that requires</span>
<span class="c"># changing the length of the data array must happen within</span>
<span class="c"># ``transform_path``.</span>
<span class="k">def</span> <span class="nf">transform_path</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">path</span><span class="p">):</span>
<span class="n">vertices</span> <span class="o">=</span> <span class="n">path</span><span class="o">.</span><span class="n">vertices</span>
<span class="n">ipath</span> <span class="o">=</span> <span class="n">path</span><span class="o">.</span><span class="n">interpolated</span><span class="p">(</span><span class="n">path</span><span class="o">.</span><span class="n">_interpolation_steps</span><span class="p">)</span>
<span class="k">return</span> <span class="n">Path</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">transform</span><span class="p">(</span><span class="n">ipath</span><span class="o">.</span><span class="n">vertices</span><span class="p">),</span> <span class="n">ipath</span><span class="o">.</span><span class="n">codes</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">inverted</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="n">HammerAxes</span><span class="o">.</span><span class="n">InvertedHammerTransform</span><span class="p">()</span>
<span class="n">inverted</span><span class="o">.</span><span class="n">__doc__</span> <span class="o">=</span> <span class="n">Transform</span><span class="o">.</span><span class="n">inverted</span><span class="o">.</span><span class="n">__doc__</span>
<span class="k">class</span> <span class="nc">InvertedHammerTransform</span><span class="p">(</span><span class="n">Transform</span><span class="p">):</span>
<span class="n">input_dims</span> <span class="o">=</span> <span class="mi">2</span>
<span class="n">output_dims</span> <span class="o">=</span> <span class="mi">2</span>
<span class="n">is_separable</span> <span class="o">=</span> <span class="bp">False</span>
<span class="k">def</span> <span class="nf">transform</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">xy</span><span class="p">):</span>
<span class="n">x</span> <span class="o">=</span> <span class="n">xy</span><span class="p">[:,</span> <span class="mi">0</span><span class="p">:</span><span class="mi">1</span><span class="p">]</span>
<span class="n">y</span> <span class="o">=</span> <span class="n">xy</span><span class="p">[:,</span> <span class="mi">1</span><span class="p">:</span><span class="mi">2</span><span class="p">]</span>
<span class="n">quarter_x</span> <span class="o">=</span> <span class="mf">0.25</span> <span class="o">*</span> <span class="n">x</span>
<span class="n">half_y</span> <span class="o">=</span> <span class="mf">0.5</span> <span class="o">*</span> <span class="n">y</span>
<span class="n">z</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">sqrt</span><span class="p">(</span><span class="mf">1.0</span> <span class="o">-</span> <span class="n">quarter_x</span><span class="o">*</span><span class="n">quarter_x</span> <span class="o">-</span> <span class="n">half_y</span><span class="o">*</span><span class="n">half_y</span><span class="p">)</span>
<span class="n">longitude</span> <span class="o">=</span> <span class="mi">2</span> <span class="o">*</span> <span class="n">np</span><span class="o">.</span><span class="n">arctan</span><span class="p">((</span><span class="n">z</span><span class="o">*</span><span class="n">x</span><span class="p">)</span> <span class="o">/</span> <span class="p">(</span><span class="mf">2.0</span> <span class="o">*</span> <span class="p">(</span><span class="mf">2.0</span><span class="o">*</span><span class="n">z</span><span class="o">*</span><span class="n">z</span> <span class="o">-</span> <span class="mf">1.0</span><span class="p">)))</span>
<span class="n">latitude</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">arcsin</span><span class="p">(</span><span class="n">y</span><span class="o">*</span><span class="n">z</span><span class="p">)</span>
<span class="k">return</span> <span class="n">np</span><span class="o">.</span><span class="n">concatenate</span><span class="p">((</span><span class="n">longitude</span><span class="p">,</span> <span class="n">latitude</span><span class="p">),</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">transform</span><span class="o">.</span><span class="n">__doc__</span> <span class="o">=</span> <span class="n">Transform</span><span class="o">.</span><span class="n">transform</span><span class="o">.</span><span class="n">__doc__</span>
<span class="k">def</span> <span class="nf">inverted</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c"># The inverse of the inverse is the original transform... ;)</span>
<span class="k">return</span> <span class="n">HammerAxes</span><span class="o">.</span><span class="n">HammerTransform</span><span class="p">()</span>
<span class="n">inverted</span><span class="o">.</span><span class="n">__doc__</span> <span class="o">=</span> <span class="n">Transform</span><span class="o">.</span><span class="n">inverted</span><span class="o">.</span><span class="n">__doc__</span>
<span class="c"># Now register the projection with matplotlib so the user can select</span>
<span class="c"># it.</span>
<span class="n">register_projection</span><span class="p">(</span><span class="n">HammerAxes</span><span class="p">)</span>
<span class="c"># Now make a simple example using the custom projection.</span>
<span class="kn">from</span> <span class="nn">pylab</span> <span class="kn">import</span> <span class="o">*</span>
<span class="n">subplot</span><span class="p">(</span><span class="mi">111</span><span class="p">,</span> <span class="n">projection</span><span class="o">=</span><span class="s">"custom_hammer"</span><span class="p">)</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">plot</span><span class="p">([</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">],</span> <span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">],</span> <span class="s">"o-"</span><span class="p">)</span>
<span class="n">grid</span><span class="p">(</span><span class="bp">True</span><span class="p">)</span>
<span class="n">show</span><span class="p">()</span>
</pre></div>
</div>
<p>Keywords: python, matplotlib, pylab, example, codex (see <a class="reference internal" href="../../faq/howto_faq.html#how-to-search-examples"><em>Search examples</em></a>)</p>
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