Bar plots are misaligned by default

[fonnesbeck]

There has been a recent change in bar plot default behavior that is causing misalignment of the bars on the y-axis. I'm not sure when this change occurred, but I will estimate 3-4 months ago.

Previously, bar plots looked like this:

However, the same code under '0.14.0-205-gbbde837' yields the following (ignore the theme differences):

So, the bars are bizarrely pushed to the right. Is matplotlib to blame for this (running 1.4.x)?

Running Python 2.7.6 (homebrew) on OS X 10.9.3.

[jorisvandenbossche]

possibly related: #6691

[sinhrks]

I'll look into this. The problem seems to occur when plotting single column without stacking. Workaround is specify stacked=True.

fig, axes = plt.subplots(2, 2)
df1 = pd.DataFrame(np.random.randn(5))
df2 = pd.DataFrame(np.random.randn(5, 2))
df1.plot(kind='bar', ax=axes[0][0], title='NG', legend=False)
df1.plot(kind='bar', stacked=True, ax=axes[0][1], title='stacked=True', legend=False)
df2.plot(kind='bar', ax=axes[1][0], title='OK', legend=False)
df2.plot(kind='bar', stacked=True, ax=axes[1][1], title='stacked=True', legend=False)

[sinhrks]

I think I could fix this... When I worked #6691, I've tried to use the same margin which is not very good (margin was asymmetric and sometimes plot was cut off, as attached in #6644). The issue is caused by this complicated logic.

The fix always takes same margin (0.25) from right/left (or top/bottom) edge of bars. If looks OK, I'll fix some tests and make a PR.