For me, if I change the script from the PR to what is shown below,
everything works fine in both Python 2.7 and 3.4 (Anaconda environments,
everything updated):
##################
url = 'http://www.libpng.org/pub/png/img_png/pngnow.png'
try:
import urllib2
data = urllib2.urlopen(url)
except Exception:
import urllib.request
from io import BytesIO
data = BytesIO(urllib.request.urlopen(url).read())
from matplotlib import pyplot
image = pyplot.imread(data) # crash on py3.x
pyplot.imshow(image)
pyplot.show()
#################
But as you can see, the Python 3 version requires the addition of BytesIO
and read(). I take it that this is not supposed to be the case.
Ryan
On Fri, Mar 20, 2015 at 11:48 AM, Ryan Nelson <rnelsonc...@gmail.com> wrote:
> Thanks, Ben. I should have made that more clear. If I run the code from
> the PR, I get the following error:
>
> Traceback (most recent call last):
> File "junk.py", line 11, in <module>
> image = pyplot.imread(data) # crash on py3.x
> File
> "/home/nelson/apps/miniconda/lib/python3.4/site-packages/matplotlib/pyplot.py",
> line 2215, in imread
> return _imread(*args, **kwargs)
> File
> "/home/nelson/apps/miniconda/lib/python3.4/site-packages/matplotlib/image.py",
> line 1270, in imread
> return handler(fname)
> RuntimeError: _image_module::readpng: file not recognized as a PNG file
>
> My code that I'm trying to port essentially does the same thing, and I get
> the same error. I ran this example just now from Anaconda Python 3.4
> install with MPL 1.4.3.
>
> My impression from the PR was that this should work out of the box now. I
> figured that maybe that was not quite the case. The implementations between
> Py2 and 3 are quite different. Figured there must be a different way that I
> wasn't aware of.
>
> Ryan
>
> On Fri, Mar 20, 2015 at 9:51 AM, Benjamin Root <ben.r...@ou.edu> wrote:
>
>> According to the PR you reference, the fix for this was merged back in
>> Jan 2013, so that means that this fix is in version 1.2.x and up. Are you
>> saying that you still can't do imread(urllib.request.urlopen(url))?
>>
>> On Thu, Mar 19, 2015 at 8:54 PM, Ryan Nelson <rnelsonc...@gmail.com>
>> wrote:
>>
>>> Hello all,
>>>
>>> I'm porting over some code that used Py2.7 urllib2.urlopen(url) to grab
>>> some image data from the net and load with pyplot.imread. It doesn't work
>>> quite right in Py3.4. I found a couple of refs:
>>>
>>> https://github.com/matplotlib/matplotlib/pull/1650
>>>
>>> http://stackoverflow.com/questions/15183170/python-crash-when-downloading-image-as-numpy-array
>>>
>>> They suggest io.BytesIO(urllib.request.urlopen(url).read()) as a
>>> replacement for Py3. Is this the best practice? Does anyone know a simpler
>>> way to do this?
>>>
>>> Ryan
>>>
>>>
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