.. 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_statistics_barchart_demo.py: =================================== Percentiles as horizontal bar chart =================================== Bar charts are useful for visualizing counts, or summary statistics with error bars. Also see the :doc:`/gallery/lines_bars_and_markers/barchart` or the :doc:`/gallery/lines_bars_and_markers/barh` example for simpler versions of those features. This example comes from an application in which grade school gym teachers wanted to be able to show parents how their child did across a handful of fitness tests, and importantly, relative to how other children did. To extract the plotting code for demo purposes, we'll just make up some data for little Johnny Doe. .. code-block:: default import numpy as np import matplotlib import matplotlib.pyplot as plt from matplotlib.ticker import MaxNLocator from collections import namedtuple np.random.seed(42) Student = namedtuple('Student', ['name', 'grade', 'gender']) Score = namedtuple('Score', ['score', 'percentile']) # GLOBAL CONSTANTS testNames = ['Pacer Test', 'Flexed Arm\n Hang', 'Mile Run', 'Agility', 'Push Ups'] testMeta = dict(zip(testNames, ['laps', 'sec', 'min:sec', 'sec', ''])) def attach_ordinal(num): """helper function to add ordinal string to integers 1 -> 1st 56 -> 56th """ suffixes = {str(i): v for i, v in enumerate(['th', 'st', 'nd', 'rd', 'th', 'th', 'th', 'th', 'th', 'th'])} v = str(num) # special case early teens if v in {'11', '12', '13'}: return v + 'th' return v + suffixes[v[-1]] def format_score(scr, test): """ Build up the score labels for the right Y-axis by first appending a carriage return to each string and then tacking on the appropriate meta information (i.e., 'laps' vs 'seconds'). We want the labels centered on the ticks, so if there is no meta info (like for pushups) then don't add the carriage return to the string """ md = testMeta[test] if md: return '{0}\n{1}'.format(scr, md) else: return scr def format_ycursor(y): y = int(y) if y < 0 or y >= len(testNames): return '' else: return testNames[y] def plot_student_results(student, scores, cohort_size): # create the figure fig, ax1 = plt.subplots(figsize=(9, 7)) fig.subplots_adjust(left=0.115, right=0.88) fig.canvas.set_window_title('Eldorado K-8 Fitness Chart') pos = np.arange(len(testNames)) rects = ax1.barh(pos, [scores[k].percentile for k in testNames], align='center', height=0.5, tick_label=testNames) ax1.set_title(student.name) ax1.set_xlim([0, 100]) ax1.xaxis.set_major_locator(MaxNLocator(11)) ax1.xaxis.grid(True, linestyle='--', which='major', color='grey', alpha=.25) # Plot a solid vertical gridline to highlight the median position ax1.axvline(50, color='grey', alpha=0.25) # Set the right-hand Y-axis ticks and labels ax2 = ax1.twinx() scoreLabels = [format_score(scores[k].score, k) for k in testNames] # set the tick locations ax2.set_yticks(pos) # make sure that the limits are set equally on both yaxis so the # ticks line up ax2.set_ylim(ax1.get_ylim()) # set the tick labels ax2.set_yticklabels(scoreLabels) ax2.set_ylabel('Test Scores') xlabel = ('Percentile Ranking Across {grade} Grade {gender}s\n' 'Cohort Size: {cohort_size}') ax1.set_xlabel(xlabel.format(grade=attach_ordinal(student.grade), gender=student.gender.title(), cohort_size=cohort_size)) rect_labels = [] # Lastly, write in the ranking inside each bar to aid in interpretation for rect in rects: # Rectangle widths are already integer-valued but are floating # type, so it helps to remove the trailing decimal point and 0 by # converting width to int type width = int(rect.get_width()) rankStr = attach_ordinal(width) # The bars aren't wide enough to print the ranking inside if width < 40: # Shift the text to the right side of the right edge xloc = 5 # Black against white background clr = 'black' align = 'left' else: # Shift the text to the left side of the right edge xloc = -5 # White on magenta clr = 'white' align = 'right' # Center the text vertically in the bar yloc = rect.get_y() + rect.get_height() / 2 label = ax1.annotate(rankStr, xy=(width, yloc), xytext=(xloc, 0), textcoords="offset points", ha=align, va='center', color=clr, weight='bold', clip_on=True) rect_labels.append(label) # make the interactive mouse over give the bar title ax2.fmt_ydata = format_ycursor # return all of the artists created return {'fig': fig, 'ax': ax1, 'ax_right': ax2, 'bars': rects, 'perc_labels': rect_labels} student = Student('Johnny Doe', 2, 'boy') scores = dict(zip(testNames, (Score(v, p) for v, p in zip(['7', '48', '12:52', '17', '14'], np.round(np.random.uniform(0, 1, len(testNames)) * 100, 0))))) cohort_size = 62 # The number of other 2nd grade boys arts = plot_student_results(student, scores, cohort_size) plt.show() .. image:: /gallery/statistics/images/sphx_glr_barchart_demo_001.png :class: sphx-glr-single-img ------------ References """""""""" The use of the following functions, methods and classes is shown in this example: .. code-block:: default matplotlib.axes.Axes.bar matplotlib.pyplot.bar matplotlib.axes.Axes.annotate matplotlib.pyplot.annotate matplotlib.axes.Axes.twinx .. rst-class:: sphx-glr-script-out Out: .. code-block:: none .. _sphx_glr_download_gallery_statistics_barchart_demo.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download :download:`Download Python source code: barchart_demo.py ` .. container:: sphx-glr-download :download:`Download Jupyter notebook: barchart_demo.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_