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1. afvincent

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   on Feb 25, 2017
2. afvincent commented on Feb 25, 2017

   

   afvincent

   on Feb 25, 2017

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   Thank you @aashil for reporting this issue.

   With the vanilla line 55 in contour.py (i.e. matplotlib.rcParams['contour.negative_linestyle'] = 'solid'), the same ValueError exception is raised when executing the script outside of building the documentation. This exception is related to the new validation scheme for line styles, see #8040. Using u'solid' instead of 'solid' makes the exception to disappear.

   @tacaswell Is it expected for such an exception to be uncaught during the CI tests?
3. afvincent

   added this to the This milestone has been deleted milestone on Feb 25, 2017
4. tacaswell commented on Feb 26, 2017

   

   tacaswell

   on Feb 26, 2017

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   We build the docs on py3 so it reasonable that we missed this.

   I think this is a unicode bug in the recently merged dash-pattern validator.
5. afvincent commented on Feb 26, 2017

   

   afvincent

   on Feb 26, 2017

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   @tacaswell It looks like you are right. With Python 2.7:

   In [1]: from matplotlib.rcsetup import _validate_linestyle
   
   In [2]: _validate_linestyle(u'solid')
   Out[2]: u'solid'
   
   In [3]: _validate_linestyle('solid')
   ---------------------------------------------------------------------------
   ValueError                                Traceback (most recent call last)
   <ipython-input-3-9192256a512f> in <module>()
   ----> 1 _validate_linestyle('solid')
   
   /home/adrien/matplotlib-git/lib/matplotlib/rcsetup.pyc in _validate_linestyle(ls)
       928 
       929     raise ValueError("linestyle must be a string or " +
   --> 930                      "an even-length sequence of floats.")
       931 
       932 
   
   ValueError: linestyle must be a string or an even-length sequence of floats.
6. afvincent commented on Feb 26, 2017

   

   afvincent

   on Feb 26, 2017

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   In _validate_linestyle(ls), should I use something like:

       ...
       if isinstance(ls, six.text_type):
           return _validate_named_linestyle(ls.decode())
       ...

   to make sure that we pass a unicode (string) argument? Or should this kind of conversion be handled differently?
7. tacaswell commented on Feb 26, 2017

   

   tacaswell

   on Feb 26, 2017

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   calling decode like that is not safe as if you are getting in a byte string you don't know what encoding it has. Further, in python 3 that will error because str has no method 'decode' (that is a bytes method).

   I do not fully understand what is going on here though.

   Python 2.7.13 (default, Dec 21 2016, 07:16:46) 
   Type "copyright", "credits" or "license" for more information.
   
   IPython 5.1.0 -- An enhanced Interactive Python.
   ?         -> Introduction and overview of IPython's features.
   %quickref -> Quick reference.
   help      -> Python's own help system.
   object?   -> Details about 'object', use 'object??' for extra details.
   
   In [1]: d = {'foo': 1, u'foo': 2}
   
   In [2]: d
   Out[2]: {'foo': 2}
   
   In [3]: d = {u'foo': 5}
   
   In [4]: 'foo' in d
   Out[4]: True
   
   In [5]: 
   
   
8. afvincent

   self-assigned this

   on Feb 27, 2017
9. afvincent commented on Feb 27, 2017

   

   afvincent

   on Feb 27, 2017

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   @tacaswell If one trusts SO, it is the expected behavior with Python 2, which “handles translation between str and unicode keys transparently for you, provided the text can be encoded to ASCII.” See for example here and there.

   About the reported issue here, I think the problem may be due to the test

   if isinstance(ls, six.text_type):

   in the _validate_linestyle function:

   Python 2.7.11 |Continuum Analytics, Inc.| (default, Dec  6 2015, 18:08:32) 
   [...]
   
   In [1]: from matplotlib.rcsetup import _validate_named_linestyle, _validate_linestyle
   
   In [2]: import six
   
   In [3]: _validate_named_linestyle('solid')  # No problem with a valid ASCII string
   Out[3]: u'solid'
   
   In [4]: _validate_linestyle('solid')  # Error with a valid ASCII string
   ---------------------------------------------------------------------------
   ValueError                                Traceback (most recent call last)
   <ipython-input-4-9192256a512f> in <module>()
   ----> 1 _validate_linestyle('solid')
   
   /home/adrien/matplotlib-git/matplotlib/lib/matplotlib/rcsetup.pyc in _validate_linestyle(ls)
       928 
       929     raise ValueError("linestyle must be a string or " +
   --> 930                      "an even-length sequence of floats.")
       931 
       932 
   
   ValueError: linestyle must be a string or an even-length sequence of floats.
   
   In [5]: isinstance('solid', six.text_type)  # => issue w/ the aforementioned test...
   Out[5]: False
   
   In [6]: isinstance(u'solid', six.text_type)  # => expected behavior
   Out[6]: True

   I used six.text_type in the current version of _validate_linestyle because it was what was used for what seemed to be similar comparisons to me in rcsetup.py, but maybe the if isinstance(ls, …) should test against six.string_types instead of six.text_type:

   from __future__ import print_function
   
   import six
   from matplotlib.rcsetup import _validate_named_linestyle
   
   
   def _validate_linestyle(ls):
       """
       A validator for all possible line styles, the named ones *and*
       the on-off ink sequences.
       """
       # Named line style, like u'--' or u'solid'
       if isinstance(ls, six.string_types):  # <= Here is the change!
           return _validate_named_linestyle(ls)
   
       # On-off ink (in points) sequence *of even length*.
       # Offset is set to None.
       try:
           if len(ls) % 2 != 0:
               # Expecting a sequence of even length
               raise ValueError
           return (None, validate_nseq_float()(ls))
       except (ValueError, TypeError):
           # TypeError can be raised by wrong types passed to float()
           # (called inside the instance of validate_nseq_float).
           pass
   
       raise ValueError("linestyle must be a string or " +
                        "an even-length sequence of floats.")
   
   # Testing different types of strings for the same valid name of line style.
   validated_strings = []
   
   for ls in ['solid', u'solid', bytes('solid')]:
       validated_strings.append(_validate_linestyle(ls))
   
   print(validated_strings)  # => [u'solid', u'solid', u'solid']
10. tacaswell commented on Feb 27, 2017

    

    tacaswell

    on Feb 27, 2017

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    Or skip the type checking and just do

    try:
        return _validate_named_linestyle(ls)
    except KeyError:
        pass
11. afvincent commented on Feb 27, 2017

    

    afvincent

    on Feb 27, 2017

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    Indeed ^^. I am going to open a PR to fix the issue as you suggest.
12. afvincent commented on Feb 27, 2017

    

    afvincent

    on Feb 27, 2017

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    With the PR #8165, I was able to locally build the documentation under Python 2.7.
13. anntzer

    closed this as completedin #8165on Mar 12, 2017