No figure shows, no error

[Yefee]

matplotlib version 1.5.1; Py 2.7.11; OSX

The code below can run smoothly without any errors, but it returns no figure when I run it as a script.
If I run it in ipython command, it's fine.
Wired!!
For other script, my python is also fine.
No ideas.

import numpy as np
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import matplotlib as mpl

def colorMapper(data):
    #_this helper function returns mapper that will normalize
    #_the colors in your dataset for plotting

    minima = min(data)
    maxima = max(data)
    norm = mpl.colors.Normalize(vmin = minima,
                                vmax = maxima,
                                clip = True)
    mapper = mpl.cm.ScalarMappable(norm = norm)
    return norm, mapper


fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

xs = [1, 1, 1, 1, 1, 1, 1, 1]
ys = [1, 1, 1, 1, 2, 2, 2, 2]
zs = [1, 2, 3, 4, 1, 2, 3, 4]
data = [1, 2, 3, 4, 1, 2, 3, 4]

norm, mapper = colorMapper(data)

for x, y, z, dat in zip(xs, ys, zs, data):
    ax.scatter(x, y, z, color = mapper.to_rgba(dat),s = dat * 10)

plt.savefig('foo.png')
fig.show()

[tacaswell]

Use plt.show instead of fig.show(). plt.show blocks and runs the GUI event loop, fig.show does not.

Compare

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot(range(3))
print('done creating artists')
# ## Switch which of these are commented out
plt.show()
# fig.show()
print('done showing')