Question

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).

Answer 1

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().

Answer 2

1.save picture which created by matplotlib
for example:plt.savefig( ./app1/static/visualize.png ) 2.use the picture in your html code for example:

about django how to use static variable(like picture and js file) you can refer to django document

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