Adventures in Machine Learning

Unlocking Demographic Insights: Creating Population Pyramids in Python

Python is quickly developing into one of the most popular data visualization programming languages on the planet. It is an efficient tool for handling large datasets, and its ability to produce a wide variety of charts and plots makes it a great choice for any data scientist.

One of the most fascinating visual representations of data is the population pyramid, which allows you to visualize the distribution of a population across different age groups.

Creating a Population Pyramid in Python

Before we can explore how to create a population pyramid, we need to make sure we are set up with all the necessary libraries and datasets. The Libraries we will be using are Pandas and Matplotlib.

Pandas is a powerful and easy-to-use data manipulation library that allows us to load our dataset. Matplotlib is a library that helps us produce high-quality graphs and charts.

To load our dataset, we will be using the World Bank’s World Development Indicators. It includes data from around 200 countries and territories and consists of over a thousand variables that outline population demographics, health, and economic standings.

Creating a Population Pyramid Plot

Now that we have everything we need, let’s create a population pyramid. We first load the World Development Indicators dataset using the Pandas library and select the desired country by specifying its name or the ISO 3 country code.

Next, we split the population data by sex. Afterward, we will extract the male and female population data from our chosen country.

We then plot the data using Matplotlibs barplot() method, specifying the sex data and age categories for the x-axis and the population count on the y-axis. When plotting a population pyramid, we invert the age categories for one of the sexes to create the desired pyramid effect.

This is done by simply reversing the order of the x-axis labels for the male group.

Interpreting a Population Pyramid

The population pyramid is an age-sex histogram that provides a snapshot of a country’s population composition. It can be used to understand the demographic profile of a country, which is necessary for making strategic planning decisions.

Population composition

In its simplest form, a population pyramid graph has two y-axes, one for males and another for females, with age categories on the x-axis. The age categories, which are usually grouped in five-year intervals, increase incrementally as you move from one side of the graph to the other.

A population pyramid with a broad base, meaning a large proportion of young people, and a narrow top, indicating a small number of aged people, is typical of developing countries with high birth rates. Conversely, a country with few children and many elderly residents has a population pyramid with a narrow base and a broad top.

Trend analysis

When analyzing population pyramids, we look for the slope and curvature of the lines. A pyramid with a wide base and a large number of children indicates a society with high birth rates, whereas a pyramid with a wide top and few children indicates low birth rates.

The pyramid’s median age, which is where the two lines cross, is another essential feature to observe. If the median age is high, the population is aging rapidly, and health care systems and social welfare programs may be strained.

However, a low median age may be typical of countries with high poverty rates and a poorly developed education system. Population pyramids can provide valuable insights into population dynamics, thus enabling researchers, policymakers, and social analysts to make better data-driven decisions.

By accurately analyzing these graphs, we can plan more effectively for a country’s future and allocate appropriate resources to areas that need it the most.


Creating population pyramids in Python may seem overwhelming to some, but it is a simple and straightforward process that can provide valuable insights into population demographics. Whether it’s planning for future healthcare systems, social welfare programs, or economic strategies, the population pyramid is an essential tool for understanding population trends.

Overall, Python’s combination of powerful data manipulation libraries coupled with high-quality data visualization tools like Matplotlib can help researchers and policymakers make informed decisions to improve people’s lives.

Code Explanation

When creating a plot in Python, there are specific actions and commands that need to be made to produce the best results. Below, we will explain the specifics of these commands in detail.

Defining x and y limits

Before creating a plot, we need to define the limits of the x and y-axis. The limits of the x-axis can be defined using the xlim() function, while the limits of the y-axis are defined using the ylim() function.

Specifying plot parameters

Next, we specify the plot’s parameters, such as the background color, title, and size. The background color of the plot can be changed using the set_facecolor() method, while the title and size can be modified using the set_title() and set_size() functions, respectively.

Creating male and female bars

We then create the male and female bars for the population pyramid. To create the bars, we specify the male and female data using the bar() method.

The bars can be colored, stacked or arranged side by side depending on the desired effect.

Adjusting grid parameters and specifying labels for y-axis

Next, we adjust grid parameters as necessary and specify the labels for the y-axis. The grid parameters can be modified using the grid() function and the labels can be modified using the set_ylabel() method, which is also used to add a description for the y-axis.

Displaying the plot

Finally, we display the plot by calling the show() method.

Plot Interpretation

After creating the plot, we need to analyze it and draw conclusions from the data we have presented. The population pyramid allows us to examine the population’s age and gender distribution trends, and from this, we can make valuable observations.

For example, if we observe that the population has a broader base on the left, this indicates a higher proportion of younger citizens. This trend can be indicative of a growing or high-growth rate population.

Conversely, if the population’s base is relatively narrow, this could indicate a population that has or is approaching a decline in birth rates, or the end of a period of high growth. Additionally, if we observe that the triangular shape of the entire pyramid is broad near the base, then narrower near the summit, this could indicate a population that has a significant proportion of young people.

This younger population comes with different social, economic, and public policy implications than an older one and may require different resources, for instance, maintaining employment opportunities or investing in educational programs. A population pyramid can also provide insights into social and economic factors.

For instance, if we observe that the proportion of males and females in a population is similar, then it implies a society that values gender equality and women’s rights. Conversely, significant disparities in the gender ratio can suggest the presence of social and economic issues that need addressing.

In conclusion, the creation of a population pyramid in Python is a valuable tool for researchers, policymakers, and social analysts. By analyzing it, we can gain insights into a population’s demographic composition, growth rates, and distribution trends.

The ability to make these informed data-driven decisions can mean the difference between a country’s prosperity or setbacks. In summary, the creation of population pyramids in Python is a straightforward process, requiring us to define x and y limits, specify plot parameters, create male and female bars, adjust grid parameters and specify labels for the y-axis, and display the plot.

These pyramids provide valuable insights into a country’s demographic composition, growth rates, distribution trends, and gender ratios. Being able to analyze these data-driven decisions can lead to informed decision-making, which can be the difference between a country’s prosperity or setbacks.

Data visualization tools like Python can greatly assist policymakers, researchers, and social analysts in planning for a nation’s future and allocating appropriate resources.

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