How to Create Bar-Plot with two y-axis/bars in Pandas

DataPlotPlus -

To make a double bar plot or plot bar graph with two y axis in Pandas you can:

  • use secondary_y - secondary_y= 'amount'
  • use subplots

Steps to plot bar chart with 2 Y-axis

  • Import matplotlib library
  • Create DataFrame with correlated data
  • Create the bar plot and axes objects
  • Plot the first variable on x and left y axes
  • Plot the second variable on x and secondary y axes

More information can be found: DataFrame.plot - secondary_y

Data

amount price
A 4 400
B 8 500
C 15 1000
D 7 600
E 3 120

Example 1 - secondary_y

import matplotlib.pyplot as plt
import pandas as pd

data = {"amount":{"A":4,"B":8,"C":15,"D":7,"E":3},
        "price":{"A":400,"B":500,"C":1000,"D":600,"E":120}}
df = pd.DataFrame(data)

_ = df.plot( kind= 'bar' , secondary_y= 'amount' , rot= 0 )
plt.show()

Output

Example 2 - secondary_y - add axis names

Create a figure and two axes:

import matplotlib.pyplot as plt
import pandas as pd

data = {"amount":{"A":4,"B":8,"C":15,"D":7,"E":3},
        "price":{"A":400,"B":500,"C":1000,"D":600,"E":120}}
df = pd.DataFrame(data)

df.plot.bar(secondary_y= 'amount')

ax1, ax2 = plt.gcf().get_axes() 
ax1.set_ylabel('price')

ax2.set_ylabel('amount')

Output

Example 3

import matplotlib.pyplot as plt
import pandas as pd

data = {"amount":{"A":4,"B":8,"C":15,"D":7,"E":3},
        "price":{"A":400,"B":500,"C":1000,"D":600,"E":120}}
df = pd.DataFrame(data)


fig = plt.figure()

ax = fig.add_subplot(111)
ax2 = ax.twinx()

width = 0.3

df.amount.plot(kind='bar', color='red', ax=ax, width=width, position=1)
df.price.plot(kind='bar', color='blue', ax=ax2, width=width, position=0)

ax.set_ylabel('Amount')
ax2.set_ylabel('Price')

plt.show()

Output

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