New answers tagged administrative-boundaries
The GADM database of Global Administrative Areas has downloadable shapefile up to level four for Viet Nam http://www.gadm.org/
I just read an article about a new... app? created by the USGS, called the Historical Topographic Map Explorer. You can search or pan, click on the map, and it will show a timeline at the bottom listing the date of all available maps. The oldest for Miami seems to be 1950 though. Another source mentioned in several answers elsewhere on this site is the ...
You are actually asking two questions. One is how to merge census data to your shape file. This is not very difficult, you may want to check out merge or spCbind, or this answer. It hard to say without knowing the structure of your data. The second question is about how to do the weighted sampling. I have a suggestion below that uses spsample from the sp ...
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