Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.

This error message is indicating that you are trying to display a Matplotlib figure using a non-GUI backend (agg), which does not support interactive display. To resolve this issue, you can switch to a GUI backend such as Tkinter or Qt, or save the figure to a file instead of displaying it interactively. Here is an example of how to switch to the Tkinter backend:

import matplotlib
matplotlib.use('TkAgg')

import matplotlib.pyplot as plt

# create and display a simple plot
x = [1, 2, 3, 4, 5]
y = [2, 4, 6, 8, 10]
plt.plot(x, y)
plt.show()

This code will use the Tkinter backend to display the plot interactively. If you want to save the plot to a file instead, you can use the `savefig` function:

plt.savefig('myplot.png')

This will save the plot as a PNG image file named `myplot.png`.