[Bug]: ValueError: Unable to determine Axes to steal space for Colorbar.

Bug summary

matplotlib==3.6.0 started raising an error when trying to add a colorbar to plt.hist():

ValueError: Unable to determine Axes to steal space for Colorbar. Either provide the cax argument to use as the Axes for the Colorbar, provide the ax argument to steal space from it, or add mappable to an Axes.

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

xs = np.random.rand(100)

_, bin_edges, bars = plt.hist(xs)
color_map = getattr(plt.cm, "hot")
for x_val, rect in zip(bin_edges, bars.patches):
    rect.set_color(color_map(x_val))

cbar = plt.colorbar(
    plt.cm.ScalarMappable(cmap=color_map),
    # cax=ax.inset_axes([0.95, 0.1, 0.05, 0.8]),
)

Actual outcome

In matplotlib==3.6.0:

Expected outcome

In matplotlib==3.5.1:

Operating system

macOS 12.6

Matplotlib Version

3.6.0

Python version

3.10

Installation

pip

The error disappears in 3.6.0 by following the error message and passing cax=ax.inset_axes([0.95, 0.1, 0.05, 0.8]).

If it is ambiguous what axes to use, pass in the axes directly:

cbar = plt.colorbar(
    plt.cm.ScalarMappable(cmap=color_map),
    ax=plt.gca()
)

You could make an axes, and use that, but you will lose some layout convenience.

Good to know I can keep auto-layout for the color bar.

If it is ambiguous what axes to use, pass in the axes directly:

What changed between 3.5.1 and 3.6.0? Why wasn't it ambiguous before?

This happened in #23740. However, I think we were under the impression this was deprecated, but it sounds like perhaps that was not the case?

I had the problem when trying to use create a simple SHAP plot using the shap package.

import shap

# use SHAP (SHapley Additive exPlanations) to explain the output of the generated model
explainer = shap.TreeExplainer(model)
shap_values = explainer.shap_values(X)
shap.summary_plot(shap_values[1], X, feature_names=X.columns, show=False, max_display=20, plot_size=(15, 10))

ValueError: Unable to determine Axes to steal space for Colorbar. Either provide the cax argument to use as the Axes for the Colorbar, provide the ax argument to steal space from it, or add mappable to an Axes.

I had to downgrade to matplotlib 3.5.1 to fix the issue.

Please report to shap

I will put on the agenda for next weeks call what we should do about this. It seems we screwed up the deprecation warning somehow, or a lot of downstream packages didn't see it.

There was a deprecation warning here, but it was only triggered if the mappable had an axes that was different from the current axes:

matplotlib/lib/matplotlib/figure.py

Lines 1182 to 1191 in a86271c

    
           if ax is None: 
        
               ax = self.gca() 
        
               if (hasattr(mappable, "axes") and ax is not mappable.axes 
        
                       and cax is None): 
        
                   _api.warn_deprecated( 
        
                       "3.4", message="Starting from Matplotlib 3.6, colorbar() " 
        
                       "will steal space from the mappable's axes, rather than " 
        
                       "from the current axes, to place the colorbar.  To " 
        
                       "silence this warning, explicitly pass the 'ax' argument " 
        
                       "to colorbar().")

In the OP's case, I think the mappable has no axes.

I guess this should get fixed for the bug release, though maybe not the most critical thing in the world. But we have probably broken a few libraries by doing this with no notice.

Is it possible to reopen this issue? I'm having the same problem with version 3.9.2. I can only plot my graphs (pyprocar and vaspkit) when I downgrade to version 3.4.2(3)

You can open a new issue, but the behaviour was deprecated, so unless there is a strong reason, you will have to either use old Matplotlib, or take the problem up with pyprocar and vaspkit.

move plot_defaults.py into pymatviz pkg

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[Bug]: ValueError: Unable to determine Axes to steal space for Colorbar. #23973

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	if ax is None:
	ax = self.gca()
	if (hasattr(mappable, "axes") and ax is not mappable.axes
	and cax is None):
	_api.warn_deprecated(
	"3.4", message="Starting from Matplotlib 3.6, colorbar() "
	"will steal space from the mappable's axes, rather than "
	"from the current axes, to place the colorbar. To "
	"silence this warning, explicitly pass the 'ax' argument "
	"to colorbar().")

[Bug]: ValueError: Unable to determine Axes to steal space for Colorbar. #23973

Description

Bug summary

Code for reproduction

Actual outcome

Expected outcome

Operating system

Matplotlib Version

Python version

Installation

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janosh commented on Sep 21, 2022

jklymak commented on Sep 21, 2022

janosh commented on Sep 21, 2022

jklymak commented on Sep 21, 2022

jvmunhoz commented on Sep 30, 2022

jklymak commented on Sep 30, 2022

rcomer commented on Sep 30, 2022

jklymak commented on Sep 30, 2022

TheGreatDeadOne commented on Sep 6, 2024

jklymak commented on Sep 6, 2024

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