matplotlib tiny_layout + gridspec + fig.suptitle 看起来很糟糕

Question

I have a very nice GridSpec graph using Matplotlib 2.2.2 but I can't make a pretty title for the figure as a whole. Example:

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

def example(tl):
    fig = plt.figure(figsize=(14,8))
    hr = [3,3,3,1,1]
    wr = [3,1]
    ny = len(hr)
    nx = len(wr)
    gs = gridspec.GridSpec(ny,nx,
                        height_ratios=hr,
                        width_ratios=wr,
                        hspace=0.08, wspace=0.1)
    for j in xrange(nx):
        ax = [fig.add_subplot(gs[0,j])]
        ax += [fig.add_subplot(gs[i,j], sharex=ax[0]) for i in xrange(1,ny)]
        for axi in ax:
              axi.plot([0,1,2],[0,1,4])    
    fig.suptitle('The quick brown fox jumps over the lazy dog.')
    if tl:
        gs.tight_layout(fig)

If I run example(False) for no tight layout I get a huge amount of space above the figures:

If I run example(True) for a tight layout I get negative space:

How can I fix this and get a figure-level title with a proper amount of margin from the subplots?

Answer 1

tight_layout() does not take figure level artists into account.

Use constrained_layout

However, there is a relatively new alternative, called constrained_layout . Using this, the figure title will be included. Note that for this to work you need to supply the figure to the GridSpec via it's figure argument.

import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

def example(tl):
    fig = plt.figure(figsize=(14,8), constrained_layout=tl)
    hr = [3,3,3,1,1]
    wr = [3,1]
    ny = len(hr)
    nx = len(wr)
    gs = gridspec.GridSpec(ny,nx, figure=fig,
                        height_ratios=hr,
                        width_ratios=wr,
                        hspace=0.08, wspace=0.1)
    for j in range(nx):
        ax = [fig.add_subplot(gs[0,j])]
        ax += [fig.add_subplot(gs[i,j], sharex=ax[0]) for i in range(1,ny)]
        for axi in ax:
              axi.plot([0,1,2],[0,1,4])    
    fig.suptitle('The quick brown fox jumps over the lazy dog.')


example(True)
plt.show()

Update top margin

Alternatively you can update the top margin after calling tight_layout . Eg as

gs.update(top=0.95)

Code:

import matplotlib.pyplot as plt
import matplotlib.gridspec as gridspec

def example(tl):
    fig = plt.figure(figsize=(14,8))
    hr = [3,3,3,1,1]
    wr = [3,1]
    ny = len(hr)
    nx = len(wr)
    gs = gridspec.GridSpec(ny,nx, figure=fig,
                        height_ratios=hr,
                        width_ratios=wr,
                        hspace=0.08, wspace=0.1)
    for j in range(nx):
        ax = [fig.add_subplot(gs[0,j])]
        ax += [fig.add_subplot(gs[i,j], sharex=ax[0]) for i in range(1,ny)]
        for axi in ax:
              axi.plot([0,1,2],[0,1,4])    
    fig.suptitle('The quick brown fox jumps over the lazy dog.')
    if tl:
        gs.tight_layout(fig)
        gs.update(top=0.95)


example(True)
plt.show()