python - Pandas Plotting with Multi-Index

Question

After performing a groupby.sum() on a DataFrame I'm having some trouble trying to create my intended plot.

How can I create a subplot (kind='bar') for each Code, where the x-axis is the Month and the bars are ColA and ColB?

Answer 1

I found the unstack(level) method to work perfectly, which has the added benefit of not needing a priori knowledge about how many Codes there are.

df.unstack(level=0).plot(kind='bar', subplots=True)

Answer 2

Using the following DataFrame ...

# using pandas version 0.14.1
from pandas import DataFrame
import pandas as pd
import matplotlib.pyplot as plt

data = {'ColB': {('A', 4): 3.0,
('C', 2): 0.0,
('B', 4): 51.0,
('B', 1): 0.0,
('C', 3): 0.0,
('B', 2): 7.0,
('Code', 'Month'): '',
('A', 3): 5.0,
('C', 1): 0.0,
('C', 4): 0.0,
('B', 3): 12.0},
'ColA': {('A', 4): 66.0,
('C', 2): 5.0,
('B', 4): 125.0,
('B', 1): 5.0,
('C', 3): 41.0,
('B', 2): 52.0,
('Code', 'Month'): '',
('A', 3): 22.0,
('C', 1): 14.0,
('C', 4): 51.0,
('B', 3): 122.0}}

df = DataFrame(data)

... you can plot the following (using cross-section):

f, a = plt.subplots(3,1)
df.xs('A').plot(kind='bar',ax=a[0])
df.xs('B').plot(kind='bar',ax=a[1])
df.xs('C').plot(kind='bar',ax=a[2])

One for A, one for B and one for C, x-axis: 'Month', the bars are ColA and ColB. Maybe this is what you are looking for.