Python Matplotlib Box plot

Question

This is my dataframe:

{'Parameter': {0: 'A', 1: 'A', 2: 'A', 3: 'A', 4: 'A', 5: 'A', 6: 'A', 7: 'A'},
 'Site': {0: 'S1',
  1: 'S2',
  2: 'S1',
  3: 'S2',
  4: 'S1',
  5: 'S2',
  6: 'S1',
  7: 'S2'},
 'Value': {0: 2.3399999999999999,
  1: 2.6699999999999999,
  2: 2.5600000000000001,
  3: 2.8900000000000001,
  4: 3.4500000000000002,
  5: 4.4500000000000002,
  6: 3.6699999999999999,
  7: 4.5599999999999996}}

I am trying to plot boxplot of parameter by site. What is an easiest way to do it? Additional question is if i will have more than 1 parameter, what will be the easiest way to plot boxplot using matplotlib by parameter? Thank you

Answer 1

You're going to want to use the DataFrame.boxplot method and group by the "Parameter" and "Site" columns.

import matplotlib.pyplot as plt
from pandas import DataFrame

df = DataFrame({'Parameter': ['A',]*8, 
                'Site': ['S1', 'S2', 'S1', 'S2', 'S1', 'S2', 'S1', 'S2'],
                'Value':  [2.34, 2.67, 2.56, 2.89, 3.45, 4.45, 3.67, 4.56]})

df.boxplot(by=['Parameter', 'Site'])
plt.show()

If you want to plot a specific column of your data, you can use the column keyword argument to boxplot.

# Plot single value
df.boxplot(column='Value', by=['Parameter', 'Site'])

# Plot Multiple values
df.boxplot(column=['Value', 'OtherValue'], by=['Parameter', 'Site'])