On Fri, 8 Aug 2008, Murray Richardson wrote:
Hello users,
I am using R to create some scripts that involve a combination of SAGA
functions (via RSAGA) and R processes. I need to read a polygon shapefile
into R, interate through each polygon feature in the attribute table, convert
it to its own shapefile, and do some processing on that individual polygon
shapefile in SAGA. I will then need to update the row's attributes (in the
original shapefile) with the results of the SAGA process.
I'm primarily looking on advice on how to read and iterate through the
shapefile rows, converting each one into a temporary shapefile. I also
appreciate advice on updating records in a shapefile attribute table.
Thanks in advance.
If the shapefile is read into a SpatialPolygonsDataFrame, then the [
subset operator works just as for other R objects. Something like:
for (i in 1:length(slot(x, "polygons"))) {
tmpx <- x[i,]
# do something with tmpx
}
will extract each Polygons object in turn as a (multi)-geometry with its
vector of attributes.
Roger
Murray Richardson
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--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: [EMAIL PROTECTED]
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