How to Change the Start and End Values on a Second Y Axis in Matplotlib Python

Learn how to easily adjust the start and end values on both Y axes in Matplotlib for your subplots. This comprehensive guide offers practical examples using Python code.
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How to Change the Start and End Values on a Second Y Axis in Matplotlib Python

When creating plots with multiple Y axes, especially in Matplotlib, you might find yourself needing to adjust the range of those axes for better visual clarity. This can be especially useful for comparing datasets with vastly different ranges on a single graph. In this guide, we'll discuss how to change the start and end values on a second Y axis using Matplotlib in Python.

The Problem: Adjusting Y Axis Ranges

You may come across a situation where you have two datasets plotted against the same x-axis, but each set of data requires its own scale. For instance, you might want the left Y-axis to range from 0 to 10000, while the right Y-axis needs to be set from 8000 to 18000. This is a common challenge when visualizing financial data or any datasets that have different magnitudes.

In the provided attempt, the user successfully modified the right Y-axis, but encountered difficulties when it came to changing the left Y-axis. Let's explore how to address this issue properly.

Solution: Setting Y Axis Limits

In Matplotlib, changing the limits of Y axes is accomplished using the set_ylim() method. Here’s how you can do it step by step:

Step 1: Create Subplots with Twin Axes

Begin by creating your subplots and initializing both the first and second Y axes using the twinx() function:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Plot Your Data

Next, you can plot your datasets on the respective axes. Here’s an example of plotting two datasets:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Set Y Axis Labels

It’s a good practice to label your axes for clarity. You can use the set_ylabel() method:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Adjust Y Axis Limits

Finally, here is the crucial part where you can set the limits for both the left and right Y axes:

[[See Video to Reveal this Text or Code Snippet]]

Complete Example

Putting it all together, here’s the complete code snippet you can use:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the steps outlined above, you can effectively manage the range of each Y axis in a dual-axis plot using Matplotlib in Python. This flexibility allows you to create complex visualizations with clarity, helping to better present your data and insights. Remember, visual clarity is key when conveying information through graphs, so always consider adjusting your axes accordingly!