implementing preserving transparency in Matplotlib bar charts when saving to PNG format
I'm dealing with I keep running into I'm currently trying to create a bar chart with transparent backgrounds using Matplotlib, but I'm running into issues when saving the figure as a PNG file... My intention is to have the bars appear against a transparent background instead of a white one. Here’s the code I’m working with: ```python import matplotlib.pyplot as plt import numpy as np # Sample data data = [5, 10, 15, 20] labels = ['A', 'B', 'C', 'D'] # Create a bar chart plt.bar(labels, data, color='blue', alpha=0.7) plt.gca().patch.set_alpha(0.0) # Set the figure background to transparent plt.savefig('bar_chart.png', transparent=True) # Attempting to save with transparency plt.show() ``` The question arises when I check the saved PNG file; the background is still white instead of transparent. I’ve looked into the `savefig` documentation, and I believe I’m using the correct `transparent=True` parameter. However, it seems like the figure's background color is overriding this. I also tried setting `plt.figure(facecolor='none')` before creating the bar chart, but that didn't seem to work either. Here’s the output warning I receive when I save the figure: ``` UserWarning: The figure is being saved with a non-transparent background. Use `transparent=True` to save with a transparent background. ``` I’m using Matplotlib version 3.5.1, and I want to ensure the final image has a transparent background. Any suggestions on how to solve this scenario? This is part of a larger CLI tool I'm building. Am I missing something obvious? This issue appeared after updating to Python 3.9. Any examples would be super helpful. I'm on Ubuntu 22.04 using the latest version of Python. Has anyone else encountered this?