st: Aggregating spatial units for SPMAP

["Karsten Pfaff" <atze1985@zedat.fu-berlin.de>]

Dear Statalist members,
I would like to refer first to the following thread that emerged some
month earlier on statalist:

http://www.stata.com/statalist/archive/2012-06/msg00384.html

My problem is similar. I have a shapefile (coordinate file) containing
polygon coordinates about a certain type of regions (calles "kreise") in
Germany, which allows me to draw a grid of Germany that divides Germany in
just these regions. However, I am not interested in the regions themselves
but in some kind of higher order regions called "ror". Of course I also
have information about which "kreise" are part of which "ror" (just
imagine you have coordinates about the counties of the USA and based on
these coordinates you would like to get the coordinates of the federal
states, knowing which countries belong to which federal state). The data
file looks as follows (illustrative example):

ror    kreise (=_ID)     _Y     _X
101        1         9.0468785	54.872552
101        1         9.0646343	54.871183
101        1         9.0649463	54.871159
101        1         9.090514   54.70260
101        2
101        2
101        2      some coordinates for kreise 2 & 3
101        2
101        2
101        2
102        3
102        3

So obviously, ror 101 contains kreise 1 and 2.
Based on these information, I would like to create a shapefile that draws
polygones of each ror, and ignores the "within" borders. Is there any
possibility to do so? I think there must be some way since all the
necessary information to create a map containing but the rors are at hand.
Any help or suggestion is highly appreciated.

Best regards Karsten Pfaff




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