value_counts() for distributions in Data Analysis Python

Introduction

We use value_counts() to quickly see how often each value appears in a list or column. It helps us understand the spread or distribution of data.

Checking how many times each product was sold in a store.

Finding the count of different answers in a survey question.

Seeing the number of times each category appears in a dataset.

Understanding the frequency of colors chosen in a design.

Counting how many students got each grade in a test.

Syntax

Data Analysis Python

Series.value_counts(normalize=False, sort=True, ascending=False, bins=None, dropna=True)

normalize=True shows proportions instead of counts.

sort=True sorts counts from highest to lowest by default.

Examples

Counts each unique value in the column and sorts from most to least.

Data Analysis Python

df['column'].value_counts()

Shows the percentage of each unique value instead of counts.

Data Analysis Python

df['column'].value_counts(normalize=True)

Sorts counts from least to most.

Data Analysis Python

df['column'].value_counts(ascending=True)

Groups numeric data into 3 equal bins and counts values in each bin.

Data Analysis Python

df['column'].value_counts(bins=3)

Sample Program

This code counts how many times each color appears in the list and then shows the percentage for each color.

Data Analysis Python

import pandas as pd

# Sample data: colors chosen by 10 people
colors = ['red', 'blue', 'red', 'green', 'blue', 'blue', 'red', 'yellow', 'green', 'blue']

# Create a pandas Series
color_series = pd.Series(colors)

# Count how many times each color appears
counts = color_series.value_counts()

# Show the counts
print(counts)

# Show the percentage of each color
percentages = color_series.value_counts(normalize=True)
print(percentages)

Important Notes

If your data has missing values, value_counts() ignores them by default.

You can use dropna=False to include missing values in the counts.

Summary

value_counts() helps you see how data is spread by counting each unique value.

You can get counts or percentages by changing the normalize option.

It works well for both numbers and categories.