Wsrtjtyk

I have a loop which selects one polygon for each iteration. I want to summarize all polygons into one spatialpolygonsdataframe in order to export it as shapefile.
refpoly

The loop could look like this:

    ref<-shapefile(reference.list[grepl(pattern, reference.list)]);ref$Id<-1:nrow(ref)

      auto<-shapefile(i);auto$Id<-1:nrow(auto)





autopolysp <- spatialpolygonsdataframe()

     #loop over polygons 

      for (j in 1:20){

        refpoly <- ref[which(ref$Id==j),];plot(refpoly)#select reference poly

        centroids <- gCentroid(refpoly);plot(centroids, add=TRUE) #id centroid of ref poly

        autopoly1 <- auto[which(gIntersects(refpoly,auto, byid=TRUE)==TRUE),];plot(autopoly1, border="red",add=TRUE)



    autopolysp[j]<-SpatialPolygons(autopoly)

        }

After the loop I wanted to combine the single shapes in the autopolysp(spatialpolygonsdataframe) with:

 autopolyplot <- SpatialPolygonsDataFrame(sapply(autopolysp))

This approach fails already at the point where I create the spdf.

I also tried to create the spdf like this:

 spl<-SpatialPolygons(list())

  data<-data.frame()

  autopolyshp = SpatialPolygonsDataFrame(spl, data)

I feel like this is a quick answer but I struggle nonetheless...

Appreciate your help..

Many thanks