8000 Convert colorbar_only example to tutorial · matplotlib/matplotlib@f8d96be · GitHub
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Commit f8d96be

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patniharshitpatniharshit
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Convert colorbar_only example to tutorial
1 parent 74fa27b commit f8d96be

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‎examples/api/colorbar_only.py

Lines changed: 63 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -1,60 +1,97 @@
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'''
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====================
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Customized colorbars
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====================
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"""
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=============================
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Customized Colorbars Tutorial
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=============================
55
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This example shows how to build colorbars without an attached mappable.
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'''
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This tutorial shows how to build colorbars without an attached mappable.
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"""
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###############################################################################
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# Customized Colorbars
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# ====================
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#
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# `matplotlib.colorbar.ColorbarBase` derives from `ScalarMappable` and puts a
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# colorbar in specified axes, it is the base class with standalone colorbar
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# drawing functionality. It can be used as-is to make a colorbar for a given
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# colormap and does not need a mappable object like an image. In this tutorial
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# we will explore what can be done with standalone colorbar.
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#
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# We will start by making a figure of desired size and adding axis at position
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# [left, bottom, width, height] where all quantities are in fractions of figure
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# width and height.
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import matplotlib.pyplot as plt
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import matplotlib as mpl
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# Make a figure and axes with dimensions as desired.
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fig = plt.figure(figsize=(8, 3))
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ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
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ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])
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ax3 = fig.add_axes([0.05, 0.15, 0.9, 0.15])
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18-
# Set the colormap and norm to correspond to the data for which
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# the colorbar will be used.
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###############################################################################
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# Basic continuous colorbar
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# -------------------------
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#
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# Set the colormap and norm to correspond to the data for which the colorbar
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# will be used. Then create the colorbar by calling `ColorbarBase` and
38+
# specify axis, colormap, norm and orientation as parameters. Here we create
39+
# a basic continuous colorbar with ticks and labels. There are many more kwargs
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# which can be used to further modify the colorbar.
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2042
cmap = mpl.cm.cool
2143
norm = mpl.colors.Normalize(vmin=5, vmax=10)
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23-
# ColorbarBase derives from ScalarMappable and puts a colorbar
24-
# in a specified axes, so it has everything needed for a
25-
# standalone colorbar. There are many more kwargs, but the
26-
# following gives a basic continuous colorbar with ticks
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# and labels.
2845
cb1 = mpl.colorbar.ColorbarBase(ax1, cmap=cmap,
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norm=norm,
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orientation='horizontal')
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cb1.set_label('Some Units')
3249

33-
# The second example illustrates the use of a ListedColormap, a
34-
# BoundaryNorm, and extended ends to show the "over" and "under"
35-
# value colors.
50+
###############################################################################
51+
# Discrete intervals colorbar
52+
# ---------------------------
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#
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# The second example illustrates the use of a ListedColormap which generates
55+
# colormap from a set of listed colors, a BoundaryNorm which generates a
56+
# colormap index based on discrete interval and extended ends to show the
57+
# "over" and "under" value colors. Over and under are used to display data
58+
# outside of the normalized [0,1] range. Here we pass colors as gray shades as
59+
# a string encoding a float in the 0-1 range.
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#
61+
# If a ListedColormap is used, the length of the bounds array must be
62+
# one greater than the length of the color list. The bounds must be
63+
# monotonically increasing.
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#
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# This time we pass some more arguments in addition to previous arguments to
66+
# ColorBase. For the out-of-range values to display on the colorbar, we have to
67+
# use the extend keyword argument. To use 'extend', you must specify two extra
68+
# boundaries. Finally spacing argument ensures that intervals are shown on
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# colorbar proportionally.
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3671
cmap = mpl.colors.ListedColormap(['r', 'g', 'b', 'c'])
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cmap.set_over('0.25')
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cmap.set_under('0.75')
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40-
# If a ListedColormap is used, the length of the bounds array must be
41-
# one greater than the length of the color list. The bounds must be
42-
# monotonically increasing.
4375
bounds = [1, 2, 4, 7, 8]
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norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
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cb2 = mpl.colorbar.ColorbarBase(ax2, cmap=cmap,
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norm=norm,
47-
# to use 'extend', you must
48-
# specify two extra boundaries:
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boundaries=[0] + bounds + [13],
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extend='both',
51-
ticks=bounds, # optional
81+
ticks=bounds,
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spacing='proportional',
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orientation='horizontal')
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cb2.set_label('Discrete intervals, some other units')
5585

56-
# The third example illustrates the use of custom length colorbar
57-
# extensions, used on a colorbar with discrete intervals.
86+
###############################################################################
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# Colorbar with custom extension lengths
88+
# --------------------------------------
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#
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# Now in the third example we illustrate the use of custom length colorbar
91+
# extensions, used on a colorbar with discrete intervals. Here we pass colors
92+
# as RGB triplet. To make the length of each extension the same as the length
93+
# of the interior colors pass extendfrac argument as auto
94+
5895
cmap = mpl.colors.ListedColormap([[0., .4, 1.], [0., .8, 1.],
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[1., .8, 0.], [1., .4, 0.]])
6097
cmap.set_over((1., 0., 0.))
@@ -66,13 +103,11 @@
66103
norm=norm,
67104
boundaries=[-10] + bounds + [10],
68105
extend='both',
69-
# Make the length of each extension
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# the same as the length of the
71-
# interior colors:
72106
extendfrac='auto',
73107
ticks=bounds,
74108
spacing='uniform',
75109
orientation='horizontal')
76110
cb3.set_label('Custom extension lengths, some other units')
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plt.show()
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‎tutorials/colors/colorbar_only.py

Lines changed: 112 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,112 @@
1+
"""
2+
=============================
3+
Customized Colorbars Tutorial
4+
=============================
5+
6+
This tutorial shows how to build colorbars without an attached mappable.
7+
8+
"""
9+
10+
###############################################################################
11+
# Customized Colorbars
12+
# ====================
13+
#
14+
# `matplotlib.colorbar.ColorbarBase` derives from `ScalarMappable` and puts a
15+
# colorbar in specified axes, it is the base class with standalone colorbar
16+
# drawing functionality. It can be used as-is to make a colorbar for a given
17+
# colormap and does not need a mappable object like an image. In this tutorial
18+
# we will explore what can be done with standalone colorbar.
19+
#
20+
# We will start by making a figure of desired size and adding axis at position
21+
# [left, bottom, width, height] where all quantities are in fractions of figure
22+
# width and height.
23+
24+
import matplotlib.pyplot as plt
25+
import matplotlib as mpl
26+
27+
fig = plt.figure(figsize=(8, 3))
28+
ax1 = fig.add_axes([0.05, 0.80, 0.9, 0.15])
29+
ax2 = fig.add_axes([0.05, 0.475, 0.9, 0.15])
30+
ax3 = fig.add_axes([0.05, 0.15, 0.9, 0.15])
31+
32+
###############################################################################
33+
# Basic continuous colorbar
34+
# -------------------------
35+
#
36+
# Set the colormap and norm to correspond to the data for which the colorbar
37+
# will be used. Then create the colorbar by calling `ColorbarBase` and
38+
# specify axis, colormap, norm and orientation as parameters. Here we create
39+
# a basic continuous colorbar with ticks and labels. There are many more kwargs
40+
# which can be used to further modify the colorbar.
41+
42+
cmap = mpl.cm.cool
43+
norm = mpl.colors.Normalize(vmin=5, vmax=10)
44+
45+
cb1 = mpl.colorbar.ColorbarBase(ax1, cmap=cmap,
46+
norm=norm,
47+
orientation='horizontal')
48+
cb1.set_label('Some Units')
49+
50+
###############################################################################
51+
# Discrete intervals colorbar
52+
# ---------------------------
53+
#
54+
# The second example illustrates the use of a ListedColormap which generates
55+
# colormap from a set of listed colors, a BoundaryNorm which generates a
56+
# colormap index based on discrete interval and extended ends to show the
57+
# "over" and "under" value colors. Over and under are used to display data
58+
# outside of the normalized [0,1] range. Here we pass colors as gray shades as
59+
# a string encoding a float in the 0-1 range.
60+
#
61+
# If a ListedColormap is used, the length of the bounds array must be
62+
# one greater than the length of the color list. The bounds must be
63+
# monotonically increasing.
64+
#
65+
# This time we pass some more arguments in addition to previous arguments to
66+
# ColorBase. For the out-of-range values to display on the colorbar, we have to
67+
# use the extend keyword argument. To use 'extend', you must specify two extra
68+
# boundaries. Finally spacing argument ensures that intervals are shown on
69+
# colorbar proportionally.
70+
71+
cmap = mpl.colors.ListedColormap(['r', 'g', 'b', 'c'])
72+
cmap.set_over('0.25')
73+
cmap.set_under('0.75')
74+
75+
bounds = [1, 2, 4, 7, 8]
76+
norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
77+
cb2 = mpl.colorbar.ColorbarBase(ax2, cmap=cmap,
78+
norm=norm,
79+
boundaries=[0] + bounds + [13],
80+
extend='both',
81+
ticks=bounds,
82+
spacing='proportional',
83+
orientation='horizontal')
84+
cb2.set_label('Discrete intervals, some other units')
85+
86+
###############################################################################
87+
# Colorbar with custom extension lengths
88+
# --------------------------------------
89+
#
90+
# Now in the third example we illustrate the use of custom length colorbar
91+
# extensions, used on a colorbar with discrete intervals. Here we pass colors
92+
# as RGB triplet. To make the length of each extension the same as the length
93+
# of the interior colors pass extendfrac argument as auto
94+
95+
cmap = mpl.colors.ListedColormap([[0., .4, 1.], [0., .8, 1.],
96+
[1., .8, 0.], [1., .4, 0.]])
97+
cmap.set_over((1., 0., 0.))
98+
cmap.set_under((0., 0., 1.))
99+
100+
bounds = [-1., -.5, 0., .5, 1.]
101+
norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
102+
cb3 = mpl.colorbar.ColorbarBase(ax3, cmap=cmap,
103+
norm=norm,
104+
boundaries=[-10] + bounds + [10],
105+
extend='both',
106+
extendfrac='auto',
107+
ticks=bounds,
108+
spacing='uniform',
109+
orientation='horizontal')
110+
cb3.set_label('Custom extension lengths, some other units')
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112+
plt.show()

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