python - How to create a grouped bar plot

Question

The goal here is to create a grouped bar plot, not subplots like the image below

Is there a simple way to create a grouped bar plot in Python? Right now I get separate bar plots, instead of separate bars on one plot.

import pandas as pd

df = pd.DataFrame([['g1', 'c1', 10], ['g1', 'c2', 12], ['g1', 'c3', 13], ['g2', 'c1', 8], ['g2', 'c2', 10], ['g2', 'c3', 12]], columns=['group', 'column', 'val'])

  group column  val
0    g1     c1   10
1    g1     c2   12
2    g1     c3   13
3    g2     c1    8
4    g2     c2   10
5    g2     c3   12
    

df.groupby(['group']).plot(kind='bar')

Answer 1

Pandas will show grouped bars by columns. Entries in each row but different columns will constitute a group in the resulting plot. Hence you need to "reshape" your dataframe to have the "group" as columns. In this case you can pivot like

df.pivot("column", "group", "val")

producing

group   g1  g2
column        
c1      10   8
c2      12  10
c3      13  12

Plotting this will result in a grouped bar chart.

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame([['g1','c1',10],['g1','c2',12],['g1','c3',13],['g2','c1',8],
                   ['g2','c2',10],['g2','c3',12]],columns=['group','column','val'])

df.pivot("column", "group", "val").plot(kind='bar')

plt.show()