你需要删除 num 参数从图构造函数和关闭，当你

  import matplotlib.pyplot 

 def test_matplotlib（request）：
f = figure（figsize =（6,6））
 .... 
 matplotlib.pyplot.close（f）
 

通过删除 num 参数，您将避免同时使用相同的数字。如果2个浏览器同时请求图像，则可能会发生这种情况。如果这不是问题，另一个可能的解决方案是使用清除方法，即 f.clear（）。

From some examples from the Internet I made the test code below. It works!

... BUT if I reload the page, the pie will draw itself with the same image. Some parts get darker every time I reload the page. When I restart the the development server, it is reset. How do I draw properly with Matplotlib in Django? It looks like it remembers some drawings...

Source views.py (let urls.py link to it):

from pylab import figure, axes, pie, title
from matplotlib.backends.backend_agg import FigureCanvasAgg

def test_matplotlib(request):
    f = figure(1, figsize=(6,6))
    ax = axes([0.1, 0.1, 0.8, 0.8])
    labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
    fracs = [15,30,45, 10]
    explode=(0, 0.05, 0, 0)
    pie(fracs, explode=explode, labels=labels, autopct='%1.1f%%', shadow=True)
    title('Raining Hogs and Dogs', bbox={'facecolor':'0.8', 'pad':5})

    canvas = FigureCanvasAgg(f)    
    response = HttpResponse(content_type='image/png')
    canvas.print_png(response)
    return response

I am using Django 1.0.1 and Python 2.6.2 (Linux).

You need to remove the num parameter from the figure constructor and close the figure when you're done with it.

import matplotlib.pyplot

def test_matplotlib(request):
    f = figure(figsize=(6,6))
    ....
    matplotlib.pyplot.close(f)

By removing the num parameter, you'll avoid using the same figure at the same time. This could happen if 2 browsers request the image at the same time. If this is not an issue, another possible solution is to use the clear method, i.e. f.clear().