warning about too many open figures

🚨 Beware of Too Many Open Figures! 🖼️

Have you ever encountered the warning message "RuntimeWarning: More than 20 figures have been opened" while working on a data visualization project using Matplotlib? Don't worry; you're not alone. In this blog post, we'll explore the common issues surrounding this warning and provide you with easy solutions to avoid it. So, let's dive in! 🏊‍♂️

Understanding the Warning

The warning message is triggered when you attempt to create more than 20 figures using the plt.subplots() function or any other pyplot interface like matplotlib.pyplot.figure. This happens because figures created through the pyplot interface are retained until explicitly closed, which can potentially consume a significant amount of memory.

But Why Do I Get the Warning?

It's easy to get confused about this warning, especially if you're clearing and deleting figures in your code. The warning doesn't indicate that you have multiple figures open simultaneously. Instead, it's a cumulative count of the figures created throughout the script's execution.

Avoid the Warning with These Solutions

Now that we understand the problem let's discuss some solutions to avoid getting this warning.

Solution 1: Explicitly Close the Figures

To prevent the accumulation of open figures, you can explicitly close each figure after you've finished working with it. Use the plt.close(fig) function to close a specific figure or plt.close('all') to close all currently open figures. Here's an example:

fig, ax = plt.subplots(...)
# do some plotting
fig.savefig(...)
plt.close(fig)  # Close the figure after use

Remember always to close the figures you're done using to free up memory for future figures.

Solution 2: Use a Context Manager

To ensure that your figures are automatically closed, you can use a context manager provided by Matplotlib. The context manager automatically closes the figure at the end of the block, even if an error occurs. Here's an example:

with plt.figure() as fig:
    # do some plotting
    fig.savefig(...)

With this approach, you don't need to worry about explicitly closing the figure. It will be taken care of by the context manager.

Take Action and Go Beyond the Warning!

Now that you have learned how to avoid the warning about too many open figures, it's time to take action:

1. Start by reviewing your code and identify any sections where you create multiple figures.

2. Check if you are explicitly closing each figure after you're done using it.

3. Consider using context managers to automate the process.

By following these steps, you can ensure your code is more memory-efficient and reduce the risk of running into this warning in the future. 🚀

Share your experience in the comments section below and let us know if you found these solutions helpful! 💬

Now go ahead and create beautiful visualizations without the worry of too many open figures! 🎨