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I am new in R and I am facing a problem. I have a list with many SpatialPolygonsDataFrames. Some of them are like this example

enter image description here

This is a SpatialPolygonsDataFrame. My "problem" is that the data.frame has two rows for this SpatialPolygonsDataFrame. How can I keep the two polygons with only one row in data.frame? I think is something like merge but how can I do this in R?

I use the sp package for geometry representation.

  • This is how the sp package stores multipart polygons (on separate rows). why do you want to merge the rows!? – Farid Cheraghi Nov 19 '15 at 11:43
  • Because I want them to have the same length (the data.frames). I will add rows and store data like area and perimeter so I want every data.frame of SpatialPolygonsDataFrames to have the same length. Is it wrong to do that? Thank you for edit. – g.f.l Nov 19 '15 at 11:49
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You can aggregate these into a multi-polygon.

library(raster)
a <- aggregate(x, 'var')

var is the variable(s) that indicates which rows need to be grouped.

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