Re: [Matplotlib-users] savefig and StringIO error on Python3

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This works for me with python 3.4.2

import matplotlib.pyplot as plt
from io import BytesIO
import base64

fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot([1,2,3])

sio = BytesIO()

fig.savefig(sio, format="png")

html = """<html><body>
<img src="data:image/png;base64,{}"/>
</body></html>""".format(base64.encodebytes(sio.getvalue()).decode())


For python 2.7.8 change html =""" to

html = """<html><body>
<img src="data:image/png;base64,%s"/>
</body></html>""" % base64.encodestring(sio.getvalue())

Best regards,
Scott


On Nov 1, 2014, at 7:37 AM, Julien Hillairet <jul...@gm...> wrote:

> Dear all,
> I'm trying to write a html page content in which a png figure is generated by matplotlib, with Python3. 
> However, the following piece of code does not work with matplotlib/Python3 (while it should work with Python2). The error is the following on
> TypeError: string argument expected, got 'bytes'
> when on fig.savefig(sio, format="png") 
> Could someone explain me how to do it ?  
> Best regards,
> Julien
> 
> --------------------------------------------
> 
> import matplotlib.pyplot as plt
> 
> from io import StringIO
> fig = plt.figure()
> ax = fig.add_subplot(111)
> ax.plot([1,2,3])
> 
> sio = StringIO()
> 
> fig.savefig(sio, format="png")
> 
> html = """<html><body>
> ...a bunch of text and html here...
> <img src="data:image/png;base64,%s"/>
> ...more text and html...
> </body></html>""" % sio.getvalue().strip()
> 
> ------------------------------------------------------------------------------