Hi,
Well when you plot, imshow or whatever is matplotlib related, the axes
do scale *automatically*.
Why should it be different with quiver?
I do reproduce your error with axis('tight')
Xavier
> Hi Xavier (cc list),
>
> It may be a bug, however I do not know what the default behaviour 'should'
> be. You could do:
>
> lims = [-4, 4, -4, 4]
> axis(lims)
>
> after calling quiver to see the whole arrow. I did notice that calling
>
> axis('tight')
>
> threw the following error
>
> /Users/Damon/python/lib/matplotlib/axes.py:2038: UserWarning: Attempting to
> set identical xmin==xmax results in singular transformations; automatically
> expanding. xmin=1.0, xmax=1.0
> warnings.warn('Attempting to set identical xmin==xmax results in singular
> transformations; automatically expanding. xmin=%s, xmax=%s'%(xmin, xmax))
> /Users/Damon/python/lib/matplotlib/axes.py:2212: UserWarning: Attempting to
> set identical ymin==ymax results in singular transformations; automatically
> expanding. ymin=1.0, ymax=1.0
> warnings.warn('Attempting to set identical ymin==ymax results in singular
> transformations; automatically expanding. ymin=%s, ymax=%s'%(ymin, ymax))
>
> is this correct, or is it a bug? I'm using "ipython -pylab" with the MacOSX
> backend. I was expecting axis('tight') would scale the axes so I could see
> the whole arrow.
>
>
> Regards,
> -- Damon
>
> --------------------------
> Damon McDougall
> Mathematics Institute
> University of Warwick
> Coventry
> CV4 7AL
> d.mcdoug...@warwick.ac.uk
>
> On 22 Nov 2009, at 21:34, Xavier Gnata wrote:
>
>
>> Hi,
>>
>> RTFM...indeed it works.
>> However, the axis do not scale accordingly:
>>
>> quiver([1],[1],[2],[2], angles='xy', scale_units='xy', scale=1) on a TkAgg
>> backend produce a plot with:
>> In [11]: axis()
>> Out[11]:
>> (0.94000000000000006,
>> 1.0600000000000001,
>> 0.94000000000000006,
>> 1.0600000000000001)
>>
>> The display area scales the same way as it does using
>> quiver([1],[1],[2],[2]) (without any other args).
>> It looks like a bug.
>>
>> Xavier
>>
>>
>>
>>> Hi Xavier,
>>>
>>> You can pass some handy keyword arguments to fix that. Use the following:
>>>
>>> quiver([1],[1],[1.2],[1.2], angles='xy', scale_units='xy', scale=1)
>>>
>>> Hope that helps :)
>>>
>>>
>>> Regards,
>>> -- Damon
>>>
>>> --------------------------
>>> Damon McDougall
>>> Mathematics Institute
>>> University of Warwick
>>> Coventry
>>> CV4 7AL
>>> d.mcdoug...@warwick.ac.uk
>>>
>>> On 22 Nov 2009, at 16:37, Xavier Gnata wrote:
>>>
>>>
>>>
>>>> Hi,
>>>>
>>>> I woud like to draw a vector field using pylab.
>>>> quivert looks nice but it sould not scale the arrows to fit my use-case.
>>>> quiver([1],[1],[1.2],[1.2]) does plot a nice arrow but the head of the
>>>> arrow is not at (1.2,1.2).
>>>> Is there a way to plot a list of arrows *without* any scaling?
>>>>
>>>> Xavier
>>>>
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>>>
>>>
>>
>
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