Matplotlib在使用savefig保存图形时不会忘记以前的数据

Question

import matplotlib.pyplot as plt
plt.plot([1,2,3],[1,2,3],'ro')
plt.axis([-4,4,-4,4])
plt.savefig('azul.png')
plt.plot([0,1,2],[0,0,0],'ro')
plt.axis([-4,4,-4,4])
plt.savefig('amarillo.png')

Output:

Why does this happen and how to solve?

Answer 1

What you see is a completely expected behaviour. You can plot as many data as often as you want to the same figure, which is very often very useful.

If you want to create several figures in the same script using the matplotlib state machine, you need to first close one figure before generating the next.

So in this very simple case, just add plt.close() between figure creation.

import matplotlib.pyplot as plt
plt.plot([1,2,3],[1,2,3],'bo')
plt.axis([-4,4,-4,4])
plt.savefig('azul.png')
plt.close()
plt.plot([0,1,2],[0,0,0],'yo')
plt.axis([-4,4,-4,4])
plt.savefig('amarillo.png')