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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

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<title>Annotating text — Matplotlib 1.5.0 documentation</title>

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<h1>Annotating text<a class="headerlink" href="#annotating-text" title="Permalink to this headline">¶</a></h1>

For a more detailed introduction to annotations, see

<a class="reference internal" href="annotations_guide.html#plotting-guide-annotation">Annotating Axes</a>.

The uses of the basic <a class="reference internal" href="../api/pyplot_api.html#matplotlib.pyplot.text" title="matplotlib.pyplot.text"><code class="xref py py-func docutils literal">text()</code></a> command above

place text at an arbitrary position on the Axes. A common use case of

text is to annotate some feature of the plot, and the

<code class="xref py py-func docutils literal">annotate()</code> method provides helper functionality

to make annotations easy. In an annotation, there are two points to

consider: the location being annotated represented by the argument

<code class="docutils literal">xy</code> and the location of the text <code class="docutils literal">xytext</code>. Both of these

arguments are <code class="docutils literal">(x,y)</code> tuples.

<div class="highlight-python"><div class="highlight"><pre>import numpy as np

import matplotlib.pyplot as plt

fig = plt.figure()

t = np.arange(0.0, 5.0, 0.01)

s = np.cos(2*np.pi*t)

line, = ax.plot(t, s, lw=2)

ax.annotate('local max', xy=(2, 1), xytext=(3, 1.5),

arrowprops=dict(facecolor='black', shrink=0.05),

)

ax.set_ylim(-2,2)

plt.show()

</pre></div>

</div>

(<a class="reference external" href="../pyplots/annotation_basic.py">Source code</a>, <a class="reference external" href="../pyplots/annotation_basic.png">png</a>, <a class="reference external" href="../pyplots/annotation_basic.hires.png">hires.png</a>, <a class="reference external" href="../pyplots/annotation_basic.pdf">pdf</a>)

</div>

In this example, both the <code class="docutils literal">xy</code> (arrow tip) and <code class="docutils literal">xytext</code> locations

(text location) are in data coordinates. There are a variety of other

coordinate systems one can choose – you can specify the coordinate

system of <code class="docutils literal">xy</code> and <code class="docutils literal">xytext</code> with one of the following strings for

<code class="docutils literal">xycoords</code> and <code class="docutils literal">textcoords</code> (default is ‘data’)

</colgroup>

<tr class="row-odd"><th class="head">argument</th>

<th class="head">coordinate system</th>

</tr>

</thead>

<tr class="row-even"><td>‘figure points’</td>

<td>points from the lower left corner of the figure</td>

</tr>

<tr class="row-odd"><td>‘figure pixels’</td>

<td>pixels from the lower left corner of the figure</td>

</tr>

<tr class="row-even"><td>‘figure fraction’</td>

<td>0,0 is lower left of figure and 1,1 is upper right</td>

</tr>

<tr class="row-odd"><td>‘axes points’</td>

<td>points from lower left corner of axes</td>

</tr>

<tr class="row-even"><td>‘axes pixels’</td>

<td>pixels from lower left corner of axes</td>

</tr>

<tr class="row-odd"><td>‘axes fraction’</td>

<td>0,0 is lower left of axes and 1,1 is upper right</td>

</tr>

<td>use the axes data coordinate system</td>

</tr>

</tbody>

</table>

For example to place the text coordinates in fractional axes

coordinates, one could do:

<div class="highlight-python"><div class="highlight"><pre>ax.annotate('local max', xy=(3, 1), xycoords='data',

xytext=(0.8, 0.95), textcoords='axes fraction',

horizontalalignment='right', verticalalignment='top',

)

</pre></div>

</div>

For physical coordinate systems (points or pixels) the origin is the

(bottom, left) of the figure or axes. If the value is negative,

however, the origin is from the (right, top) of the figure or axes,

analogous to negative indexing of sequences.

Optionally, you can specify arrow properties which draws an arrow

from the text to the annotated point by giving a dictionary of arrow

properties in the optional keyword argument <code class="docutils literal">arrowprops</code>.

</colgroup>

<tr class="row-odd"><th class="head"><code class="docutils literal">arrowprops</code> key</th>

<th class="head">description</th>

</tr>

</thead>

<tr class="row-even"><td>width</td>

<td>the width of the arrow in points</td>

</tr>

<td>the fraction of the arrow length occupied by the head</td>

</tr>

<tr class="row-even"><td>headwidth</td>

<td>the width of the base of the arrow head in points</td>

</tr>

<tr class="row-odd"><td>shrink</td>

<td>move the tip and base some percent away from

the annotated point and text</td>

</tr>

<tr class="row-even"><td>**kwargs</td>

<td>any key for <a class="reference internal" href="../api/patches_api.html#matplotlib.patches.Polygon" title="matplotlib.patches.Polygon"><code class="xref py py-class docutils literal">matplotlib.patches.Polygon</code></a>,

e.g., <code class="docutils literal">facecolor</code></td>

</tr>

</tbody>

</table>

In the example below, the <code class="docutils literal">xy</code> point is in native coordinates

(<code class="docutils literal">xycoords</code> defaults to ‘data’). For a polar axes, this is in

(theta, radius) space. The text in this example is placed in the

fractional figure coordinate system. <a class="reference internal" href="../api/text_api.html#matplotlib.text.Text" title="matplotlib.text.Text"><code class="xref py py-class docutils literal">matplotlib.text.Text</code></a>

keyword args like <code class="docutils literal">horizontalalignment</code>, <code class="docutils literal">verticalalignment</code> and

<code class="docutils literal">fontsize are passed from the `~matplotlib.Axes.annotate` to the

``Text</code> instance

<div class="highlight-python"><div class="highlight"><pre>import numpy as np

import matplotlib.pyplot as plt

fig = plt.figure()

ax = fig.add_subplot(111, polar=True)

r = np.arange(0,1,0.001)

theta = 2*2*np.pi*r

line, = ax.plot(theta, r, color='#ee8d18', lw=3)

ind = 800

thisr, thistheta = r[ind], theta[ind]

ax.plot([thistheta], [thisr], 'o')

ax.annotate('a polar annotation',

xy=(thistheta, thisr), # theta, radius

xytext=(0.05, 0.05), # fraction, fraction

textcoords='figure fraction',

horizontalalignment='left',

verticalalignment='bottom',

)

plt.show()

</pre></div>

</div>

(<a class="reference external" href="../pyplots/annotation_polar.py">Source code</a>, <a class="reference external" href="../pyplots/annotation_polar.png">png</a>, <a class="reference external" href="../pyplots/annotation_polar.hires.png">hires.png</a>, <a class="reference external" href="../pyplots/annotation_polar.pdf">pdf</a>)

</div>

For more on all the wild and wonderful things you can do with

annotations, including fancy arrows, see <a class="reference internal" href="annotations_guide.html#plotting-guide-annotation">Annotating Axes</a>

and <a class="reference internal" href="../examples/pylab_examples/annotation_demo.html#pylab-examples-annotation-demo">pylab_examples example code: annotation_demo.py</a>.

</div>

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Last updated on Oct 29, 2015.

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