在R中提取具有多边形的点 [英] Extracting points with polygon in R

问题描述

我正在尝试使用'sp'包函数'over'通过多边形提取点

I'm trying to extract points by a polygon using the 'sp' package function 'over'

library(sp)
library(rgeos)
#my polygon plgn (many polygon features in one)
plot(plgn)
proj4string(plgn) = CRS("+proj=utm +zone=46 +datum=WGS84 +units=m +no_defs")
#giving spatial reference to point data d
coordinates(d) <- ~X+Y
proj4string(d) = CRS("+proj=utm +zone=46 +datum=WGS84 +units=m +no_defs")
#USE overlay (there are many NAs)
overlay=d[!is.na(over(d, plgn)),]

不幸的是，我收到一个错误消息

Unfortunately, I'm getting an ERROR

Error in d[!is.na(over(d, plgn)), ] : 
matrix argument not supported in SpatialPointsDataFrame selection

有什么主意吗?是因为我的多边形包含100个要素吗?

Any idea?? Is it because my polygon contains 100s of features?

推荐答案

您的plgn是SpatialPolygonsDataFrame，因此，is.na(over(d, plgn))返回逻辑矩阵.这不能用于子集SpatialPoints*.您可以执行以下操作将逻辑矩阵转换为子设置操作可以容纳的向量:

Your plgn is a SpatialPolygonsDataFrame, and as such, is.na(over(d, plgn)) returns a logical matrix. This cannot be used to subset your SpatialPoints*. You can do the following to convert the logical matrix to a vector that the subsetting operation can accommodate:

d[complete.cases(over(d, plgn)), ]

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