PR Summary

I made a little change so that now the anchor argument in make_axes_gridspec mimic the behavior of that in make_axes. Now the postion of colorbar is determined by anchor and shrink, should be very useful when shrink < 1.0

The effect is demostrated in the plot below. Now I can place the colorbar at different place with different shrinked size.

import numpy as np
import matplotlib as mpl
import matplotlib,pyplot as plt

x = np.random.randn(100)
y = np.random.randn(100)
fig = plt.figure()
ax = fig.add_subplot()
mappable = ax.scatter(x,y, c=y)
ax.figure.colorbar(mappable, ax=ax, anchor=(0,0.3), shrink=0.5) 

Before the change, we can achieve that using ax.figure.colorbar(mappable, ax=ax, anchor=(0,0.3), use_gridspec=False) , however, this will create a colorbar as a Axes not a Subplot, when I use subplots_ajust to adjust the border margins, I got the following plot.

fig = plt.figure()
ax = fig.add_subplot()
mappable = ax.scatter(x,y, c=y)
ax.figure.colorbar(mappable, ax=ax, anchor=(0,0.3), shrink=0.5, use_gridspec=False) 
ax.figure.subplots_adjust(bottom=0.1)

It seems the colorbar Axes is ignored and my plot is re-placed according to its panchor parameter that make_axes set. It bothers me when I have multiple plots and wanna adjust the plots border margins and wspace, hspace.

gridspec offers a better approach and is the default setting when creating a colorbar, however, I want the colorbar to be 0.5 size and placed at the bottom right, which is mot implemented.

So this is what I did basically.

PR Checklist

• Has Pytest style unit tests
• Code is Flake 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way