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I am trying to iterate over the rows of a spatial polygon data frame in R, but cannot figure out the right indexing. I don't want to select by attributes, but rather just iterate over the spatial polygon data frame.

  • Could you give some sample code, indicate what you've tried? – Simbamangu Jul 16 '15 at 17:35
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If you do not need to apply a conditional subset, you can just use a bracket index on rows, without referencing the @data slot.

library(sp)
data(meuse)
coordinates(meuse) <- ~x+y

# Subset first observation and plot
p <- meuse[1,]
  plot(meuse, pch=20)
  plot(p, pch=20, cex=1.5, col="red", add=TRUE) 

# display elev value for each observation
for(i in 1:nrow(meuse)) {
  p <- meuse[i,]
  cat("elev", i, p@data$elev, "\n")
}
  • That is it. I was missing the comma in p <-meuse[1,] – user44796 Jul 16 '15 at 18:39

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