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Bug report

plt.stackplot with non-default 'baseline' keyword option not working for integer input.

I wanted to use plt.stackplot with the baseline='sym' option, and noticed that it a TypeError with my data. Turned out it was just a matter of changin the input valued to float types, but it should work for integer arrays too.

Code for reproduction

def fnx():
    return np.random.randint(5, 50, 10)

x = np.arange(10)
y1, y2, y3 = fnx(), fnx(), fnx()

fig, ax = plt.subplots()
ax.stackplot(x, y1, y2, y3, baseline="sym")
plt.show()

Actual outcome

TypeError: Cannot cast ufunc add output from dtype('float64') to dtype('int64') with casting rule 'same_kind'

Expected outcome

This nice figure:

Matplotlib version

• Matplotlib version, Python version and Platform (Windows, OSX, Linux ...)
  version

>>> matplotlib.__version__
1.5.3
>>>matplotlib.pylab.__version__
1.11.3

Python version 2.7.12
Platform OSX Version 10.12

• How did you install Matplotlib and Python (pip, anaconda, from source ...)
  pip