Re: [matplotlib-devel] basemap domain changes on pyplot call

I have since switched over to the svn checkout of basemap, and this issue
appears to be 'fixed'.  While readshapefile() does still load all of the
data, it appears that .set_axes_limits() automatically turns off
autoscaling.  This should cut down on much of the "odd" behaviors users
would encounter.  FWIW, I was using v0.99.2 from the Fedora repos.

Ben Root

On Fri, May 21, 2010 at 4:57 PM, Benjamin Root <ben...@ou...> wrote:

> I did some more digging and I think I have a hypothesis for what is
> happening.
>
> There is only one main difference between a call to .drawstates() and
> .readshapefiles() with respect to loading and plotting data.  .drawstates()
> loads *only* the line segments that coincide with the defined map
> boundaries, while .readshapefiles() loads all of the data in the shapefile.
> Therefore, the LineCollection that gets attached to the axis contains data
> from outside the stated domain.
>
> In addition, the basemap versions of the plotting functions have the
> benefit of finishing their calls with a call to .set_axes_limits(), which
> keeps the axes in check.  However, a non-basemap version would not call that
> automatically, thereby having its axes automatically expanded to contain all
> of the data in the LineCollection.
>
> I am not sure what exactly should be done about this.  This is certainly
> un-intuitive behavior, though. Maybe there could be a keyword option in
> .readshapefile() to have only the data for the stated domain loaded?  That
> might solve the issue.
>
> Thanks,
> Ben Root
>
>
> On Fri, May 21, 2010 at 4:08 PM, Benjamin Root <ben...@ou...> wrote:
>
>> Hello,
>>
>> I have been tracking down an annoying (but easily worked around) issue
>> with Basemap.  It seems that if you call .readshapefile() to create, for
>> example, roads on your image, and then call any pyplot command afterwards
>> for that axis, the axis will reset itself to the entire domain (I guess it
>> would be the complete domain stated in the shapefile, maybe?).  This does
>> not happen if you call the equivalent function from the Basemap instance,
>> though.  Also, this does not happen with drawstates() and its ilk.
>>
>> I have made a test script and a couple of supporting shapefile in a tar.gz
>> file to demonstrate the issue.  It is available here:
>> http://dl.dropbox.com/u/7325604/basemaptest.tar.gz
>>
>>
>> I have also attached a png file showing the resulting image as it appears
>> on my computer.  I have no clue as to the cause and I hope that someone here
>> might have an idea.
>>
>> Thanks,
>> Ben Root
>>
>
>