Matplotlib - missing some ticks when sharing an axis between subplots

Question

I'm trying to make a figure consisting of 2 subplots with a shared y axis, however some 'ticks' are missing. An example:

import matplotlib.pyplot as plt
import pandas as pd

df_a = pd.DataFrame({"Foo" : pd.Series(['A','B','C']), "Bar" : pd.Series([1,2,3])})
df_b = pd.DataFrame({"Foo" : pd.Series(['B','C','D']), "Bar" : pd.Series([4,5,6])})

fig, axes = plt.subplots(nrows=1, ncols=2, sharex= True, sharey=True)

df_a.plot.barh("Foo", "Bar", ax=axes[0], legend=False, title="df_a")
df_b.plot.barh("Foo", "Bar", ax=axes[1], legend=False, title="df_b")

produces the plot below (tick labels are mixed up):

What I was expecting to see is something like this (produced using R):

What am I missing here?

jezrael · Accepted Answer · 2017-01-18 10:29:19Z

1

You need same indexes, so one possible solution is concat:

df = pd.concat([df_a.set_index('Foo'), df_b.set_index('Foo')], axis=1)
df.columns = ['a','b']
print (df)
     a    b
A  1.0  NaN
B  2.0  4.0
C  3.0  5.0
D  NaN  6.0

df.a.plot.barh(ax=axes[0], legend=False, title="df_a")
df.b.plot.barh(ax=axes[1], legend=False, title="df_b")

Another solution is set_index and reindex by union of indexes:

df_a = df_a.set_index('Foo')
df_b = df_b.set_index('Foo')
df_a = df_a.reindex(df_a.index.union(df_b.index))
df_b = df_b.reindex(df_a.index.union(df_b.index))
print (df_a)
     Bar
Foo     
A    1.0
B    2.0
C    3.0
D    NaN

print (df_b)
     Bar
Foo     
A    NaN
B    4.0
C    5.0
D    6.0



df_a.plot.barh( ax=axes[0], legend=False, title="df_a")
df_b.plot.barh( ax=axes[1], legend=False, title="df_b")

edited Jan 18, 2017 at 10:29

answered Jan 18, 2017 at 10:24

jezrael

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1 Comment

dratewka Over a year ago

The pd.concat trick works like a charm and fits nicely with the rest of my workflow. Thanks!

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