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Re: st: -spmap- reason for no aspect() option?


From   "Sergiy Radyakin" <serjradyakin@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: -spmap- reason for no aspect() option?
Date   Tue, 26 Aug 2008 21:58:08 -0400

Hello Dan,

1. Correct me if I am wrong, but the most probable reason that
aspect() option is not implemented is the following:
http://en.wikipedia.org/wiki/Map_projection

E.g. Americans commonly use Mercator, while Russians prefer Albers
projection. The difference can be very large and depends on the
distance from the equator. The transformation between most (all?)
projection pairs is non-linear and can't be implemented as
stretching/squeezing maps. -spmap- (and -tmap-) were developed for GIS
graphs in Stata.

2. Have you tried ADePT map (-amap-)?

http://siteresources.worldbank.org/INTPOVRES/Images/MainWindow2.png

http://siteresources.worldbank.org/INTPOVRES/Resources/477227-1184622288835/4002237-1219247341749/ADePT_Maps2.pdf

It works with standard shapefiles. Don't know what your data format
is, but just in case.

3. If you want to adjust aspect ratio yourself, multiplying/dividing
one of your coordinates by a constant (C>0) will do the trick. C>1
will stretch the graph in that dimension, C<1 will squeeze it in that
dimension.


Hope this helps.

Best regards,
    Sergiy Radyakin




On 8/26/08, Dan Weitzenfeld <dan.weitzenfeld@emsense.com> wrote:
> Hi All,
> Firstly, -spmap- is absolutely amazing, excellent work Maurizio Pisati.
> My question is about the lack of an aspect() option.  Is there a
> technical reason why it wasn't included?
> Basically, I am using -spmap- to draw data collected from an
> eye-tracker, and I have to stretch some of my graphs so that they
> match the aspect ratio of the stimuli.  My fear is that if there is a
> technical reason why aspect() wasn't included - e.g., it's determined
> by the data - I may be distorting my results.
> Thanks,
> Dan
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