Matplotlib tight_layout() doesn't take into account figure suptitle

Question

If I add a subtitle to my matplotlib figure it gets overlaid by the subplot\'s titles. Does anybody know how to easily take care of that? I tried the tight_layout()

Answer 1

Tight layout doesn't work with suptitle, but constrained_layout does. See this question Improve subplot size/spacing with many subplots in matplotlib

I found adding the subplots at once looked better, i.e.

fig, axs = plt.subplots(rows, cols, constrained_layout=True)

# then iterating over the axes to fill in the plots

But it can also be added at the point the figure is created:

fig = plt.figure(constrained_layout=True)

ax1 = fig.add_subplot(cols, rows, 1)
# etc

Note: To make my subplots closer together, I was also using

fig.subplots_adjust(wspace=0.05)

and constrained_layout doesn't work with this :(

Answer 2

An alternative and simple to use solution is to adjust the coordinates of the suptitle text in the figure using the y argument in the call of suptitle (see the docs):

import numpy as np
import matplotlib.pyplot as plt

f = np.random.random(100)
g = np.random.random(100)
fig = plt.figure()
fig.suptitle('Long Suptitle', y=1.05, fontsize=24)
plt.subplot(121)
plt.plot(f)
plt.title('Very Long Title 1', fontsize=20)
plt.subplot(122)
plt.plot(g)
plt.title('Very Long Title 2', fontsize=20)
plt.show()

Answer 3

As mentioned by others, by default the tight layout does not take suptitle into account. However, I have found it is possible to use the bbox_extra_artists argument to pass in the suptitle as a bounding box that should be taken into account:

st = fig.suptitle("My Super Title")
plt.savefig("figure.png", bbox_extra_artists=[st], bbox_inches='tight')

This forces the tight layout calculation to take the suptitle into account, and it looks as you would expect.

Answer 4

You can adjust the subplot geometry in the very tight_layout call as follows:

fig.tight_layout(rect=[0, 0.03, 1, 0.95])

As it's stated in the documentation (https://matplotlib.org/users/tight_layout_guide.html):

tight_layout() only considers ticklabels, axis labels, and titles. Thus, other artists may be clipped and also may overlap.

Answer 5

One thing you could change in your code very easily is the fontsize you are using for the titles. However, I am going to assume that you don't just want to do that!

Some alternatives to using fig.subplots_adjust(top=0.85):

Usually tight_layout() does a pretty good job at positioning everything in good locations so that they don't overlap. The reason tight_layout() doesn't help in this case is because tight_layout() does not take fig.suptitle() into account. There is an open issue about this on GitHub: https://github.com/matplotlib/matplotlib/issues/829 [closed in 2014 due to requiring a full geometry manager - shifted to https://github.com/matplotlib/matplotlib/issues/1109 ].

If you read the thread, there is a solution to your problem involving GridSpec. The key is to leave some space at the top of the figure when calling tight_layout, using the rect kwarg. For your problem, the code becomes:

Using GridSpec

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

f = np.random.random(100)
g = np.random.random(100)

fig = plt.figure(1)
gs1 = gridspec.GridSpec(1, 2)
ax_list = [fig.add_subplot(ss) for ss in gs1]

ax_list[0].plot(f)
ax_list[0].set_title('Very Long Title 1', fontsize=20)

ax_list[1].plot(g)
ax_list[1].set_title('Very Long Title 2', fontsize=20)

fig.suptitle('Long Suptitle', fontsize=24)    

gs1.tight_layout(fig, rect=[0, 0.03, 1, 0.95])  

plt.show()

The result:

Maybe GridSpec is a bit overkill for you, or your real problem will involve many more subplots on a much larger canvas, or other complications. A simple hack is to just use annotate() and lock the coordinates to the 'figure fraction' to imitate a suptitle. You may need to make some finer adjustments once you take a look at the output, though. Note that this second solution does not use tight_layout().

Simpler solution (though may need to be fine-tuned)

fig = plt.figure(2)

ax1 = plt.subplot(121)
ax1.plot(f)
ax1.set_title('Very Long Title 1', fontsize=20)

ax2 = plt.subplot(122)
ax2.plot(g)
ax2.set_title('Very Long Title 2', fontsize=20)

# fig.suptitle('Long Suptitle', fontsize=24)
# Instead, do a hack by annotating the first axes with the desired 
# string and set the positioning to 'figure fraction'.
fig.get_axes()[0].annotate('Long Suptitle', (0.5, 0.95), 
                            xycoords='figure fraction', ha='center', 
                            fontsize=24
                            )
plt.show()

The result:

[Using Python 2.7.3 (64-bit) and matplotlib 1.2.0]

Answer 6

The only thing that worked for me was modifying the call to suptitle:

fig.suptitle("title", y=.995)