保存为png图片

fig = plt.gcf()
print "ImageSave Done!"
fig.savefig(outPut)

保存为base64文件

先保存为png图片，然后将其转化为base64文件

figfile = BytesIO()
fig.savefig(figfile, format='png')
figfile.seek(0)  # rewind to beginning of file
figdata_png = base64.b64encode(figfile.getvalue())