Thanks Jeff,

To clarify, I'm sampling a numpy array (regular lon/lat grid) and  
extracting a series of same size frames (say 60 longitude grids and 30  
latitude grids) around a feature of interest, which can be centered  
somewhere on the map. What I want to do is accumulate statistics with  
these frames such that the relative size/distances are persevered,  
which of course means that I can't just add a frame centered on 30N  
with one centered on 80N. Ideally, I'd like to interpolate each frame  
to a common point (lon/lat) and display the results either in the  
common grid space or as radial distances from the common point.

Since you're a meteorologist I can simply say I'm creating an ensemble  
average of extra tropical cyclones from a dozen or so computer models  
(each with very different resolutions). I want to see how cloud and  
precipitation features in each model's cyclones compare to a similar  
product I'm producing from satellite data using weather model output  
to locate the cyclones. Much the same thing as the link I provided.

Thanks for your suggests as transform_scalar sounds like a good place  
to begin.

Mike

On Dec 11, 2007, at 4:57 PM, Jeff Whitaker wrote:

> mbauer wrote:
>> Matplotlib users, I looking to tap your wealth of ideas and  
>> experience  to help solve a problem I'm working on.
>>
>> The problem: I have a series of 2d scalar arrays representing a  
>> fixed  width/height lon/lat box centered on an arbitrary lon/lat. I  
>> need to  average these composites on a common basis that  
>> accommodates the scale  changes due to latitude, preferably by  
>> shifting everything to a common  central lon/lat (a polar/radial  
>> distance basis would work too). I want  a plot of the end result  
>> too and I'm like to do everything with  matplotlib and python so  
>> that it folds into the rest of my program.
>>
>> Something similar can be seen at 
>> http://www.atmos.washington.edu/~robwood/topic_cyclones.htm
>>
>> I've been looking at transform_scalar from basemap but I'm not  
>> quite  sure this is what I should use.
>>
> Mike:
>
> transform_scalar does simple bilinear interpolation from a lat/lon  
> grid to a regular grid in map projection coordinates. If your map  
> projection is just a lat/lon projection, then this amounts to  
> interpolating from one lat/lon grid to another.
>> If anyone can offer a solution, a point in the right direction, or   
>> just wave me off this path I'd be most appreciative.
>>
> I'm sure numpy/matplotlib can do what you need to do.   Matplotlib  
> can certainly make a plot similar to the one given in your link.  I  
> think you question relates more to the processing of your arrays  
> though, and not specifically the plotting.  Are all your 2d arrays  
> the same shape (the same number of lats and lons)?  Are they just  
> centered on different regions?  If so, I think you can just multiply  
> each grid point by the cosine of latitude to get the proper area  
> weighting before summing them together.  But perhaps I'm missing the  
> essence of your question ....
>
> -Jeff
>
>
> -- 
> Jeffrey S. Whitaker         Phone  : (303)497-6313
> Meteorologist               FAX    : (303)497-6449
> NOAA/OAR/PSD  R/PSD1        Email  : [EMAIL PROTECTED]
> 325 Broadway                Office : Skaggs Research Cntr 1D-124
> Boulder, CO, USA 80303-3328 Web    : http://tinyurl.com/5telg
>
>


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