Re: [matplotlib-devel] [SciPy-user] recursion limit in plot

[Ryan M. <rm...@gm...>]

John Hunter wrote:
> On Thu, Jan 15, 2009 at 4:58 PM, Ryan May <rm...@gm...> wrote:
> 
>> Ok, my debugging tells me the problem comes down to the units support,
>> specifically this code starting at line 130 in units.py:
>>
>>        if converter is None and iterable(x):
>>            # if this is anything but an object array, we'll assume
>>            # there are no custom units
>>            if isinstance(x, np.ndarray) and x.dtype != np.object:
>>                return None
>>
>>            for thisx in x:
>>                converter = self.get_converter( thisx )
>>                return converter
>>
>> Because a string is iterable, and even a single character is considered iterable,
>> this code recurses forever.  I can think this can be solved by, in addition to
>> the iterable() check, make sure that x is not string like.  If it is, this will
>> return None as the converter.  Somehow, this actually will then plot properly.
>> I'm still trying to run down why this works, but I'm running out of time for the
>> day.  I will say that the data set for the line2D object is indeed a masked array
>>  of dtype ('|S4').
>>
>> Anyone object to adding the check?
> 
> Nope -- good idea

Ok, I'll check it in when I have a chance to run backend_driver.py and makes sure
nothing breaks. (Not that it should).  I'll also take a crack at adding a test.

For future reference, plotting lists/arrays of strings works (at least for lines)
because Path calls .astype() on the arrays passed in, which will do the
conversion for us.  So (part of) matplotlib actually does support plotting
sequences of string representations of numbers, it was just hindered by the unit
check.

>> In addition, why are we looping over thisx in x but returning inside the loop?
>> Wouldn't this *always* be the same as x[0]?
> 
> The loop works for generic iterables that are not indexable and also
> for length 0 iterables
Ok, that makes sense.

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma