Adventures in Machine Learning

Mastering Stacked Bar Charts in Pandas: A Data Analyst’s Guide

Data visualization is an essential tool in the analysis of data as it helps in understanding complex information and identifying patterns. One such data visualization technique available in Python’s Pandas library is the stacked bar chart.

In this article, we will explore how to create a stacked bar chart in Pandas and understand how it can be used to interpret data. 1) Creating a Stacked Bar Chart in Pandas:

Syntax for creating stacked bar chart:

The syntax for creating a stacked bar chart in Pandas is straightforward.

It involves grouping the data by the desired category and plotting it in a stacked bar chart format. The essential keywords to keep in mind while creating a stacked bar chart in Pandas are “stacked bar chart,” “syntax,” and “Pandas.”

Example of creating stacked bar chart with pandas:

Let’s understand this better by considering an example data frame.

Suppose we have a data frame with columns “year,” “gender,” and “count,” representing the number of births by gender and year. To create a stacked bar chart showing the number of births by gender and year, we can use the following syntax:


df.groupby([‘year’, ‘gender’]).size().unstack().plot(kind=’bar’, stacked=True)


In this code, we used the groupby method to group the data based on the “year” and “gender” columns and the size method to get the count of births for each group.

The unstack method is used to create a two-dimensional table, where each row represents a year, and each column represents a gender. Finally, the plot method is used with kind=’bar’ to create a bar chart and stacked=True to create a stacked bar chart.

2) Understanding the Pandas DataFrame Example:

Description of basketball player DataFrame used in example:

As an example, let’s consider a Pandas DataFrame of basketball players’ statistics from the 2016-2017 NBA season. The data frame has six columns: “Name,” “Team,” “Position,” “Age,” “Height,” and “Weight.” The data frame contains information about various basketball players’ teams, positions, age, height, and weight.

Interpretation of the stacked bar chart generated from the DataFrame:

Let’s say we want to analyze the distribution of players by team and position. To create a stacked bar chart showing the number of players by team and position, we can use the following syntax:


df.groupby([‘Team’, ‘Position’]).size().unstack().plot(kind=’bar’, stacked=True)


The resulting stacked bar chart will display the number of players by position for each team.

This graph can help us understand the distribution of players by position and team. For instance, we can observe that the Boston Celtics and Utah Jazz have more players who play the shooting guard position than other teams.


In conclusion, a stacked bar chart is a useful visualization tool to understand categorical data’s distribution. We can create a stacked bar chart in Pandas using simple syntax by grouping data, size method, and plot method.

By using an example of a basketball player data frame, we have explained how a stacked bar chart can help us understand the distribution of players by team and position. Pandas’ stacked bar chart can be a handy tool in presenting data efficiently and effectively, making it an essential tool for data analysts, particularly those who deal with categorical data.

3) Customizing the Stacked Bar Chart:

In addition to creating a stacked bar chart, we can customize the chart’s appearance to make it more visually appealing and informative. Here are two ways to customize a stacked bar chart in Pandas:

Using color argument to modify bar chart colors:

By default, Pandas assigns a different color to each stacked bar in the bar chart, which may not always be ideal for differentiating between categories.

Still, we can convert the colors by explicitly passing a color parameter to the plot method. The syntax for doing this is the below:


df.groupby([‘Team’, ‘Position’]).size().unstack().plot(kind=’bar’, stacked=True, color=[‘#FF5733’, ‘#C70039’, ‘#900C3F’, ‘#581845’],)


This code will create a stacked bar chart with four different colors for each stacked bar, as specified by the color argument.

We can specify the color using the hexadecimal representation of the color code or by using the color names. Using title argument to add title to the bar chart:

In a stacked bar chart, it is essential to include a title to make it easier for the audience to understand the data’s message.

We can add a title to the stacked bar chart by using the title argument in the plot method. The syntax for doing this is as follows:


df.groupby([‘Team’, ‘Position’]).size().unstack().plot(kind=’bar’, stacked=True, color=[‘#FF5733’, ‘#C70039’, ‘#900C3F’, ‘#581845′], title=’NBA Players by Team and Position’)


This code will create a stacked bar chart with the title “NBA Players by Team and Position” positioned at the top of the chart.

We can customize the font size, color, and style of the title by passing additional arguments to the title method. 4) Additional Resources:

To gain a better understanding of Pandas and stacked bar charts, we recommend checking out the following resources:

– Official Pandas documentation: This documentation provides an in-depth explanation of Pandas and includes tutorials and examples on how to use Pandas to manipulate and visualize data.

– DataCamp: DataCamp offers a vast collection of courses and tutorials on data science techniques, including Pandas. The courses include interactive exercises and quizzes to reinforce your learning.

– Stack Overflow: Stack Overflow is a community-driven Q&A platform where data scientists and programmers can find solutions to common programming problems. – Kaggle: Kaggle is a platform for data scientists to share and collaborate on data science projects.

The website includes a section on Pandas, with various datasets and kernels for users to practice with. By exploring these resources, you can build your knowledge and skills in working with Pandas and creating stacked bar charts, and leverage the power of data visualization to make informed decisions.

Data visualization is an integral part of analyzing complex information and identifying patterns in data. In Python’s Pandas library, creating a stacked bar chart is a useful technique to achieve this purpose.

This article has explained how to create a stacked bar chart in Pandas, customize the chart’s appearance for visual appeal, and understand the data interpretation using an example of basketball player statistics. The article has also highlighted various resources to gain further knowledge on Pandas and stacked bar charts.

Creating stacked bar charts can be an essential tool for data analysts working with categorical data to provide effective and efficient data presentations for decision-making.

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