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Boxplot Demo

Example boxplot code

import numpy as np
import matplotlib.pyplot as plt

# Fixing random state for reproducibility

# fake up some data
spread = np.random.rand(50) * 100
center = np.ones(25) * 50
flier_high = np.random.rand(10) * 100 + 100
flier_low = np.random.rand(10) * -100
data = np.concatenate((spread, center, flier_high, flier_low))
fig1, ax1 = plt.subplots()
ax1.set_title('Basic Plot')


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb114c3df60>, <matplotlib.lines.Line2D object at 0x7fb114c3d048>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb114c3d8d0>, <matplotlib.lines.Line2D object at 0x7fb114c13390>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb114c3dcc0>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb1146f4518>], 'fliers': [<matplotlib.lines.Line2D object at 0x7fb1146f42e8>], 'means': []}
fig2, ax2 = plt.subplots()
ax2.set_title('Notched boxes')
ax2.boxplot(data, notch=True)


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb113e887f0>, <matplotlib.lines.Line2D object at 0x7fb113e88ba8>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb113e88ef0>, <matplotlib.lines.Line2D object at 0x7fb113e7e278>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb113e886a0>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb113e7e5c0>], 'fliers': [<matplotlib.lines.Line2D object at 0x7fb113e7e908>], 'means': []}
green_diamond = dict(markerfacecolor='g', marker='D')
fig3, ax3 = plt.subplots()
ax3.set_title('Changed Outlier Symbols')
ax3.boxplot(data, flierprops=green_diamond)


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb113c908d0>, <matplotlib.lines.Line2D object at 0x7fb113c90c88>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb113c90fd0>, <matplotlib.lines.Line2D object at 0x7fb113db1358>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb113c90780>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb113db16a0>], 'fliers': [<matplotlib.lines.Line2D object at 0x7fb113db19e8>], 'means': []}
fig4, ax4 = plt.subplots()
ax4.set_title('Hide Outlier Points')
ax4.boxplot(data, showfliers=False)


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb113b87518>, <matplotlib.lines.Line2D object at 0x7fb113b878d0>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb113b87c18>, <matplotlib.lines.Line2D object at 0x7fb113b87f60>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb113b873c8>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb113b61160>], 'fliers': [], 'means': []}
red_square = dict(markerfacecolor='r', marker='s')
fig5, ax5 = plt.subplots()
ax5.set_title('Horizontal Boxes')
ax5.boxplot(data, vert=False, flierprops=red_square)


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb113d842e8>, <matplotlib.lines.Line2D object at 0x7fb113d846a0>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb113d849e8>, <matplotlib.lines.Line2D object at 0x7fb113d84d30>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb113d84198>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb113d680b8>], 'fliers': [<matplotlib.lines.Line2D object at 0x7fb113d68400>], 'means': []}
fig6, ax6 = plt.subplots()
ax6.set_title('Shorter Whisker Length')
ax6.boxplot(data, flierprops=red_square, vert=False, whis=0.75)


{'whiskers': [<matplotlib.lines.Line2D object at 0x7fb113e304a8>, <matplotlib.lines.Line2D object at 0x7fb113e31358>], 'caps': [<matplotlib.lines.Line2D object at 0x7fb113e316a0>, <matplotlib.lines.Line2D object at 0x7fb113e319e8>], 'boxes': [<matplotlib.lines.Line2D object at 0x7fb113e305c0>], 'medians': [<matplotlib.lines.Line2D object at 0x7fb113e31d30>], 'fliers': [<matplotlib.lines.Line2D object at 0x7fb113e4b0b8>], 'means': []}

Fake up some more data

spread = np.random.rand(50) * 100
center = np.ones(25) * 40
flier_high = np.random.rand(10) * 100 + 100
flier_low = np.random.rand(10) * -100
d2 = np.concatenate((spread, center, flier_high, flier_low))
data.shape = (-1, 1)
d2.shape = (-1, 1)

Making a 2-D array only works if all the columns are the same length. If they are not, then use a list instead. This is actually more efficient because boxplot converts a 2-D array into a list of vectors internally anyway.

data = [data, d2, d2[::2,0]]
fig7, ax7 = plt.subplots()
ax7.set_title('Multiple Samples with Different sizes')


The use of the following functions, methods, classes and modules is shown in this example:

import matplotlib


<function boxplot at 0x7fb11b15fd08>

Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery