.. note:: :class: sphx-glr-download-link-note Click :ref:here  to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_text_labels_and_annotations_legend_demo.py: =========== Legend Demo =========== Plotting legends in Matplotlib. There are many ways to create and customize legends in Matplotlib. Below we'll show a few examples for how to do so. First we'll show off how to make a legend for specific lines. .. code-block:: python from __future__ import (absolute_import, division, print_function, unicode_literals) import matplotlib.pyplot as plt import numpy as np from matplotlib.legend_handler import (HandlerLineCollection, HandlerTuple) import matplotlib.collections as mcol from matplotlib.lines import Line2D t1 = np.arange(0.0, 2.0, 0.1) t2 = np.arange(0.0, 2.0, 0.01) fig, ax = plt.subplots() # note that plot returns a list of lines. The "l1, = plot" usage # extracts the first element of the list into l1 using tuple # unpacking. So l1 is a Line2D instance, not a sequence of lines l1, = ax.plot(t2, np.exp(-t2)) l2, l3 = ax.plot(t2, np.sin(2 * np.pi * t2), '--o', t1, np.log(1 + t1), '.') l4, = ax.plot(t2, np.exp(-t2) * np.sin(2 * np.pi * t2), 's-.') ax.legend((l2, l4), ('oscillatory', 'damped'), loc='upper right', shadow=True) ax.set_xlabel('time') ax.set_ylabel('volts') ax.set_title('Damped oscillation') plt.show() .. image:: /gallery/text_labels_and_annotations/images/sphx_glr_legend_demo_001.png :class: sphx-glr-single-img Next we'll demonstrate plotting more complex labels. .. code-block:: python x = np.linspace(0, 1) fig, (ax0, ax1) = plt.subplots(2, 1) # Plot the lines y=x**n for n=1..4. for n in range(1, 5): ax0.plot(x, x**n, label="n={0}".format(n)) leg = ax0.legend(loc="upper left", bbox_to_anchor=[0, 1], ncol=2, shadow=True, title="Legend", fancybox=True) leg.get_title().set_color("red") # Demonstrate some more complex labels. ax1.plot(x, x**2, label="multi\nline") half_pi = np.linspace(0, np.pi / 2) ax1.plot(np.sin(half_pi), np.cos(half_pi), label=r"$\frac{1}{2}\pi$") ax1.plot(x, 2**(x**2), label="$2^{x^2}$") ax1.legend(shadow=True, fancybox=True) plt.show() .. image:: /gallery/text_labels_and_annotations/images/sphx_glr_legend_demo_002.png :class: sphx-glr-single-img Here we attach legends to more complex plots. .. code-block:: python fig, axes = plt.subplots(3, 1) top_ax, middle_ax, bottom_ax = axes top_ax.bar([0, 1, 2], [0.2, 0.3, 0.1], width=0.4, label="Bar 1", align="center") top_ax.bar([0.5, 1.5, 2.5], [0.3, 0.2, 0.2], color="red", width=0.4, label="Bar 2", align="center") top_ax.legend() middle_ax.errorbar([0, 1, 2], [2, 3, 1], xerr=0.4, fmt="s", label="test 1") middle_ax.errorbar([0, 1, 2], [3, 2, 4], yerr=0.3, fmt="o", label="test 2") middle_ax.errorbar([0, 1, 2], [1, 1, 3], xerr=0.4, yerr=0.3, fmt="^", label="test 3") middle_ax.legend() bottom_ax.stem([0.3, 1.5, 2.7], [1, 3.6, 2.7], label="stem test") bottom_ax.legend() plt.subplots_adjust(hspace=0.7) plt.show() .. image:: /gallery/text_labels_and_annotations/images/sphx_glr_legend_demo_003.png :class: sphx-glr-single-img Now we'll showcase legend entries with more than one legend key. .. code-block:: python fig, (ax1, ax2) = plt.subplots(2, 1) # First plot: two legend keys for a single entry p1 = ax1.scatter([1], [5], c='r', marker='s', s=100) p2 = ax1.scatter([3], [2], c='b', marker='o', s=100) # plot returns a list, but we want the handle - thus the comma on the left p3, = ax1.plot([1, 5], [4, 4], 'm-d') # Assign two of the handles to the same legend entry by putting them in a tuple # and using a generic handler map (which would be used for any additional # tuples of handles like (p1, p3)). l = ax1.legend([(p1, p3), p2], ['two keys', 'one key'], scatterpoints=1, numpoints=1, handler_map={tuple: HandlerTuple(ndivide=None)}) # Second plot: plot two bar charts on top of each other and change the padding # between the legend keys x_left = [1, 2, 3] y_pos = [1, 3, 2] y_neg = [2, 1, 4] rneg = ax2.bar(x_left, y_neg, width=0.5, color='w', hatch='///', label='-1') rpos = ax2.bar(x_left, y_pos, width=0.5, color='k', label='+1') # Treat each legend entry differently by using specific HandlerTuples l = ax2.legend([(rpos, rneg), (rneg, rpos)], ['pad!=0', 'pad=0'], handler_map={(rpos, rneg): HandlerTuple(ndivide=None), (rneg, rpos): HandlerTuple(ndivide=None, pad=0.)}) plt.show() .. image:: /gallery/text_labels_and_annotations/images/sphx_glr_legend_demo_004.png :class: sphx-glr-single-img Finally, it is also possible to write custom objects that define how to stylize legends. .. code-block:: python class HandlerDashedLines(HandlerLineCollection): """ Custom Handler for LineCollection instances. """ def create_artists(self, legend, orig_handle, xdescent, ydescent, width, height, fontsize, trans): # figure out how many lines there are numlines = len(orig_handle.get_segments()) xdata, xdata_marker = self.get_xdata(legend, xdescent, ydescent, width, height, fontsize) leglines = [] # divide the vertical space where the lines will go # into equal parts based on the number of lines ydata = ((height) / (numlines + 1)) * np.ones(xdata.shape, float) # for each line, create the line at the proper location # and set the dash pattern for i in range(numlines): legline = Line2D(xdata, ydata * (numlines - i) - ydescent) self.update_prop(legline, orig_handle, legend) # set color, dash pattern, and linewidth to that # of the lines in linecollection try: color = orig_handle.get_colors()[i] except IndexError: color = orig_handle.get_colors()[0] try: dashes = orig_handle.get_dashes()[i] except IndexError: dashes = orig_handle.get_dashes()[0] try: lw = orig_handle.get_linewidths()[i] except IndexError: lw = orig_handle.get_linewidths()[0] if dashes[0] is not None: legline.set_dashes(dashes[1]) legline.set_color(color) legline.set_transform(trans) legline.set_linewidth(lw) leglines.append(legline) return leglines x = np.linspace(0, 5, 100) fig, ax = plt.subplots() colors = plt.rcParams['axes.prop_cycle'].by_key()['color'][:5] styles = ['solid', 'dashed', 'dashed', 'dashed', 'solid'] lines = [] for i, color, style in zip(range(5), colors, styles): ax.plot(x, np.sin(x) - .1 * i, c=color, ls=style) # make proxy artists # make list of one line -- doesn't matter what the coordinates are line = [[(0, 0)]] # set up the proxy artist lc = mcol.LineCollection(5 * line, linestyles=styles, colors=colors) # create the legend ax.legend([lc], ['multi-line'], handler_map={type(lc): HandlerDashedLines()}, handlelength=2.5, handleheight=3) plt.show() .. image:: /gallery/text_labels_and_annotations/images/sphx_glr_legend_demo_005.png :class: sphx-glr-single-img .. _sphx_glr_download_gallery_text_labels_and_annotations_legend_demo.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download :download:Download Python source code: legend_demo.py  .. container:: sphx-glr-download :download:Download Jupyter notebook: legend_demo.ipynb  .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery _