I'm hoping this is a simple question, but I have not been able to find
any answers in the archives or in my own dabbling. I have downloaded
the ZCTA Boundary files from the Census site and through SAS code
translated it to a map dataset (which I think I did right, but if
anyone else has written code to do the same thing, it might be nice to
double check the process).
My hope is to map my data by zip code (using the ZCTA map dataset I
created), but clip the zip codes at county boundaries.
One thought I have had (but not tried yet in hopes of an easier
method) is to create a different map dataset for the counties I'm
looking at by "merging" (only a psuedo-merge) the zip code map with
the county map and some how decipher which boundaries to include on
the output (somehow identify when the zip code boundary leaves the
county boundary and manually clip the map). This doesn't seem like a
real viable option (especially since I can't think of a good way of
determing the zip code boundaries within the county), but if it's the
only way and anyone has any tips it would be appreciated.
Another thought I had was to draw the zip code map and then "overlay"
the county map on top of the zip code and perhaps the "white space"
around the county map will coverup the zip space outside the county.
Hopefully that makes sense. Again, I haven't been successful at
trying this method, so any help in this direction would also be
I would think the easiest method would be to pass on a "clipping
boundary" to Proc GMap or Proc GProject(?) to limit the drawing, but
I'm not sure the Proc supports anything like that.
Again, any help would be appreciated. Thank you in advance.