[R] Problem with converting a list of grids to a list of polygons

TypeTwo Pinkert at students.uni-marburg.de
Sun Jun 15 17:04:19 CEST 2014


For a spatial analysis (its visualization) I need to produce a map of
conditions and traits. 
When I used SpatialPixelsDataFrame (sp package) my grid cells were regular
and between each row was a small gap, which is not only messy but incorrect.
So I generated the coords of each grid from the centroids in order to
elongate the cells manually (or does anybody know another way to solve

But I got stuck when I tried to convert the XMIN, XMAX, YMIN, YMAX - corner
points to a list of polygons (and keeping at least the ID as individuell

I really don’t get it, how can I read data of this format as a list of
„head"(ID, XMIN, XMAX, YMIN, YMAX,  lat, lng, altc_mean) 

polys <- Polygons(list(Polygon(assemblage[,c("XMIN", "XMAX", "YMIN",
"YMAX“)])), ID=assemblage$ID) 
SP <- SpatialPolygons(polys) 
SPDF <- SpatialPolygonsDataFrame(SP, data=data.frame(x= assemblage$lng, y=
assemblage$lat, row.names=row.names(SP))) 

Already thanks for your help, 

View this message in context: http://r.789695.n4.nabble.com/Problem-with-converting-a-list-of-grids-to-a-list-of-polygons-tp4692142.html
Sent from the R help mailing list archive at Nabble.com.

More information about the R-help mailing list