[Python] How to add deep colored edges to the bars of a histogram with the same filled color...

I was using matplotlib to plot a histogram. Usually, I use edgecolor to specify the color of the edges. And if I don't, there will be no edges.

But, I just created a pdf of a histogram which has deep colored edges with the same filled color of the bars, however I did not set the edgecolor parameter. Strangely, if I change the format to png, the final plot will not have colored edges.



The plotting code is :

x1 = np.random.normal(0, 0.8, 1000)
x2 = np.random.normal(-2, 1, 1000)
x3 = np.random.normal(3, 2, 1000)

fig = plt.figure()
ax = fig.add_subplot()
plt.hist(data, alpha=0.3, histtype='barstacked', bins=40)
fig.savefig('barstacked.pdf')
fig.savefig('barstacked.png', dpi=750)


Even stranger, if I set histtype='stepfilled', the histograms in both pdf and png formats have no colored edges.



fig = plt.figure()
ax = fig.add_subplot()
plt.hist(data, alpha=0.3, histtype='stepfilled', bins=40)
fig.savefig('stepfilled.pdf')
fig.savefig('stepfilled.png', dpi=750)


Does anyone know what parameters can be set to get this colored edge in matplotlib, or is this automatically obtained when rendering pdf?

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