使用matplotlib给我以下警告：“UserWarning：tight_layout：

Question

Try to do a graph using python matplotlib: but keep getting the following waring message:

"UserWaring: tight_layout: falling back to Agg renderer  warnings.warn("tight_layout: falling back to Agg renderer")

My code is below:

plt.legend(loc='upper left',prop = {'size':7},bbox_to_anchor=(1,1))
plt.tight_layout(pad=7)
plt.xlabel ('Build')
plt.ylabel ('Time/Sec')
plt.title ('Performance Test')
plt.grid()
plt.show()

How to fix that warning message?

Answer 1

Are you using MacOSX? It seems to be a known and open issue

https://github.com/matplotlib/matplotlib/issues/1852

I will suggest to reorganize the code such that you will use Figure instead of pyplot. You can get the Figure from plt.figure() method. Then, on the Figure instance call set_tight_layout(True). Try this example code:

import matplotlib
matplotlib.use('pdf')
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(1,1,1)
fig.set_tight_layout(True)
fig.savefig('asd.pdf')  # No warning now

As a side note, have a look at matplotlib documentation

tight_layout() can take keyword arguments of pad, w_pad and h_pad. These control the extra padding around the figure border and between subplots. The pads are specified in fraction of fontsize.

http://matplotlib.org/users/tight_layout_guide.html

This suggest that your code

plt.tight_layout(pad=7)

is wrong, as the value of pad should be between 0 and 1.