pcolorfast fails in master when image is not uniform

[u55]

Hi matplotlib developers,

When using master with python 2.7 on Linux, I discovered that pcolorfast fails if the image grid is not uniformly spaced. Here is a minimal working example:

import numpy as np
import matplotlib.pyplot as plt

Z = np.arange(6).reshape((3, 2))
X = np.array([0,1,2,10])  # <-- nonuniform array
Y = np.array([0,1,2])

plt.figure()
ax = plt.subplot(111)
ax.pcolorfast(X,Y,Z.T)  # <-- fails
# ax.pcolormesh(X,Y,Z.T)  # <-- works

plt.show()

This works fine in version 1.4.3, but fails in master with the following traceback:

Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/matplotlib/backends/backend_qt5.py", line 341, in resizeEvent
    self.draw()
  File "/usr/lib/python2.7/site-packages/matplotlib/backends/backend_qt5agg.py", line 143, in draw
    FigureCanvasAgg.draw(self)
  File "/usr/lib/python2.7/site-packages/matplotlib/backends/backend_agg.py", line 475, in draw
    self.figure.draw(self.renderer)
  File "/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 60, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/matplotlib/figure.py", line 1094, in draw
    func(*args)
  File "/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 60, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/matplotlib/axes/_base.py", line 2096, in draw
    a.draw(renderer)
  File "/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 60, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/matplotlib/image.py", line 881, in draw
    im = self.make_image(renderer.get_image_magnification())
  File "/usr/lib/python2.7/site-packages/matplotlib/image.py", line 869, in make_image
    bg)
TypeError: integer argument expected, got float

The same failure occurs with all of the backends that I have tried; which are specificially the wxagg, gtkagg, tkagg, and pdf backends.

Thanks for the help.

[tacaswell]

@u55 Can you see if the patch in #4228 fixes the problem for you and you get the result you expect?

[u55]

@tacaswell Yes, #4228 completely fixes the problem for me. Thank you.