Drawing Histogram(s) For A Pandas Dataframe

Overview:

  • A histogram is a frequency plot. Each interval data is marked with different heights based on the frequency of the data in that interval. Higher the frequency greater the height marked for that frequency.
  • Calling the hist() method on the plot member of a DataFrame instance draws the histogram for each column present in the DataFrame.
  • Number of bins or intervals of the histogram is specified for all the columns of the DataFrame combined. 
  • Each histogram will be drawn in an overlapping(if any) fashion using the alpha-blending value specified.

Example:

# Example Python program that plots

# histograms for weekly data

import pandas as pds

import matplotlib.pyplot as plot

 

# Data

dailyClosingPrices = [(10.2, 9.8),

 (9.4, 10.4),

 (8.9, 11.1),

 (9.0, 10.5), 

 (9.1, 9.4)

];

 

# The index

index   = ["Mon", "Tue", "Wed", "Thu", "Fri"];

 

# Column labels

columns = ["Week1", "Week2"];

 

# Create a DataFrame instance

df = pds.DataFrame(data=dailyClosingPrices, index = index, columns = columns);

 

# Draw histograms for weekly closing prices

df.plot.hist(bins=4, alpha=0.5, title="Weekly Histograms for daily closing prices");

plot.show(block=True);

 

Output:

Drawing histogram for the columns of a pandas DataFrame


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