matplotlib colorbar in each subplot

Question

I would like to add a separate colorbar to each subplot in a 2x2 plot.

fig , ( (ax1,ax2) , (ax3,ax4)) = plt.subplots(2, 2,sharex = True,sharey=True)
z1_plot = ax1.scatter(x,y,c = z1,vmin=0.0,vmax=0.4)
plt.colorbar(z1_plot,cax=ax1)
z2_plot = ax2.scatter(x,y,c = z2,vmin=0.0,vmax=40)
plt.colorbar(z1_plot,cax=ax2)
z3_plot = ax3.scatter(x,y,c = z3,vmin=0.0,vmax=894)
plt.colorbar(z1_plot,cax=ax3)
z4_plot = ax4.scatter(x,y,c = z4,vmin=0.0,vmax=234324)
plt.colorbar(z1_plot,cax=ax4)
plt.show()

I thought that this is how you do it, but the resulting plot is really messed up; it just has an all grey background and ignores the set_xlim , set_ylim commands I have (not shown here for simplicity). + it shows no color bars. Is this the right way to do it?

I also tried getting rid of the "cax = ...", but then the colorbar all goes on the bottom right plot and not to each separate plot!

Is plt.colorbar(z1_plot,cax=ax2)supposed to be plt.colorbar(z2_plot,cax=ax2), etc for 3 and 4? For subplots and colorbars, I would look into AxesGrid — oschoudhury
– oschoudhury, Commented May 26, 2014 at 20:08

Heberto Mayorquin · Accepted Answer · 2018-02-28 19:51:27Z

78

This can be easily solved with the the utility make_axes_locatable. I provide a minimal example that shows how this works and should be readily adaptable:

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable

import numpy as np

m1 = np.random.rand(3, 3)
m2 = np.arange(0, 3*3, 1).reshape((3, 3))

fig = plt.figure(figsize=(16, 12))
ax1 = fig.add_subplot(121)
im1 = ax1.imshow(m1, interpolation='None')

divider = make_axes_locatable(ax1)
cax = divider.append_axes('right', size='5%', pad=0.05)
fig.colorbar(im1, cax=cax, orientation='vertical')

ax2 = fig.add_subplot(122)
im2 = ax2.imshow(m2, interpolation='None')

divider = make_axes_locatable(ax2)
cax = divider.append_axes('right', size='5%', pad=0.05)
fig.colorbar(im2, cax=cax, orientation='vertical');

answered Feb 28, 2018 at 19:51

Heberto Mayorquin

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Comments

jayesef · Accepted Answer · 2017-06-21 12:01:43Z

62

In plt.colorbar(z1_plot,cax=ax1), use ax= instead of cax=, i.e. plt.colorbar(z1_plot,ax=ax1)

answered Jun 21, 2017 at 12:01

jayesef

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1 Comment

IljaBek Over a year ago

to add: fig.colorbar(sm, ax=fig.get_axes()) would add colorbar over both

Patrick Sanan · Accepted Answer · 2020-07-15 16:18:15Z

56

Specify the ax argument to matplotlib.pyplot.colorbar(), e.g.

import numpy as np
import matplotlib.pyplot as plt

fig, ax = plt.subplots(2, 2)
for i in range(2):
    for j in range(2):
         data = np.array([[i, j], [i+0.5, j+0.5]])
         im = ax[i, j].imshow(data)
         plt.colorbar(im, ax=ax[i, j])

plt.show()

edited Jul 15, 2020 at 16:18

answered Mar 19, 2019 at 15:58

Patrick Sanan

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Comments

Pepe Mandioca · Accepted Answer · 2019-02-22 15:37:10Z

34

Please have a look at this matplotlib example page. There it is shown how to get the following plot with four individual colorbars for each subplot: enter image description here

I hope this helps.
You can further have a look here, where you can find a lot of what you can do with matplotlib.

edited Feb 22, 2019 at 15:37

Pepe Mandioca

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answered May 26, 2014 at 20:06

user3413108

1 Comment

Avi Vajpeyi Over a year ago

Another matplotlib example: matplotlib.org/stable/gallery/subplots_axes_and_figures/…

uqzzhao · Accepted Answer · 2020-03-09 12:56:28Z

4

Try to use the func below to add colorbar:

def add_colorbar(mappable):
    from mpl_toolkits.axes_grid1 import make_axes_locatable
    import matplotlib.pyplot as plt
    last_axes = plt.gca()
    ax = mappable.axes
    fig = ax.figure
    divider = make_axes_locatable(ax)
    cax = divider.append_axes("right", size="5%", pad=0.05)
    cbar = fig.colorbar(mappable, cax=cax)
    plt.sca(last_axes)
    return cbar

Then you codes need to be modified as:

fig , ( (ax1,ax2) , (ax3,ax4)) = plt.subplots(2, 2,sharex = True,sharey=True)
z1_plot = ax1.scatter(x,y,c = z1,vmin=0.0,vmax=0.4)
add_colorbar(z1_plot)

answered Mar 9, 2020 at 12:56

uqzzhao

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