matplotlib: plot multiple columns of pandas data frame on the bar chart

Question

I am using the following code to plot a bar-chart:

import matplotlib.pyplot as pls 
my_df.plot(x='my_timestampe', y='col_A', kind='bar') 
plt.show()

The plot works fine. However, I want to improve the graph by having 3 columns: 'col_A', 'col_B', and 'col_C' all on the plot. Like in the example figure below:

I would like the col_A displayed in blue above x-axis, col_B in red below x-axis, and col_C in green above x-axis. Is this something possible in matplotlib? How do I make changes to plot all the three columns? Thanks!

Solution 1

You can plot several columns at once by supplying a list of column names to the plot's y argument.

df.plot(x="X", y=["A", "B", "C"], kind="bar")

This will produce a graph where bars are sitting next to each other.

In order to have them overlapping, you would need to call plot several times, and supplying the axes to plot to as an argument ax to the plot.

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

y = np.random.rand(10,4)
y[:,0]= np.arange(10)
df = pd.DataFrame(y, columns=["X", "A", "B", "C"])

ax = df.plot(x="X", y="A", kind="bar")
df.plot(x="X", y="B", kind="bar", ax=ax, color="C2")
df.plot(x="X", y="C", kind="bar", ax=ax, color="C3")

plt.show()

Solution 2

Although the accepted answer works fine, since v0.21.0rc1 it gives a warning

UserWarning: Pandas doesn't allow columns to be created via a new attribute name

Instead, one can do

df[["X", "A", "B", "C"]].plot(x="X", kind="bar")

Comments

[ImportanceOfBeingErnest]

The second plot only makes sense if the highest values are those from the first column plotted for all bars. This seems to be the case in the desired output from the question. Otherwise I would not recommend using this kind of plot and instead either use a stacked plot or the grouped bars from the first solution here. Of course one could experiment with transparency (alpha) and see if the latter solution gives an appealing result.

[ekauffmann]

this answer is marked as correct, but it should be updated with @ageorge 's answer, since in newer versions it throws a warning

[ImportanceOfBeingErnest]

@ekauffmann I cannot reproduce this. Even in the newest version of pandas (0.23.3) this does not throw a warning for me. Which version are you using?

[Akash Desai]

x='X' what exactly its ??

[Bartli]

@Akash Desai: it tells pandas the name of the colum ("X" in this case) to be plotted onto the x-axis.