汇总来自 sf::st_intersection() 几何重叠的属性

Question

我想总结一组几何图形的属性，对它们重叠的值求和。

library(devtools)
install_github("r-spatial/sf")
library(sf)
m = rbind(c(0,0), c(1,0), c(1,1), c(0,1), c(0,0))
p = st_polygon(list(m))
n = rbind(c(0.5,0.5), c(1.5,0.5), c(1.5,1.5), c(0.5,1.5), c(0.5,0.5))
q = st_polygon(list(n))
s = st_sfc(list(p, q))
sf = st_sf(s, att=c(1,1))
d = st_intersection(sf)
d$id <- 1:nrow(d)

plot(d['att'])
plot(st_centroid(d['att']), add = TRUE, col = 'red')

> d
#Simple feature collection with 3 features and 4 fields
#geometry type:  POLYGON
#dimension:      XY
#bbox:           xmin: 0 ymin: 0 xmax: 1.5 ymax: 1.5
#epsg (SRID):    NA
#proj4string:    NA
#  att                       geometry n.overlaps origins id
#1   1 POLYGON ((1 0.5, 1 0, 0 0, ...          1       1  1
#2   1 POLYGON ((0.5 1, 1 1, 1 0.5...          2    1, 2  2
#3   1 POLYGON ((0.5 1, 0.5 1.5, 1...          1       2  3

在上面提供的最小示例中，我想对 d$att 求和并得到几何 #2 的 att=2（对应于重叠的那个）。

任何帮助将不胜感激。

Answer 1

您可以使用origins 列表列来检索“起源”相交的多边形，然后对它们的att 列求和。像这样的东西可以工作（至少在这个非常简单的用例中......）：

for (int in seq_along(d$id)) {
     d$att[int] = sum(sf[d$origins[[int]], ]$att, na.rm = TRUE)
}
> d
Simple feature collection with 3 features and 4 fields
geometry type:  POLYGON
dimension:      XY
bbox:           xmin: 0 ymin: 0 xmax: 1.5 ymax: 1.5
epsg (SRID):    NA
proj4string:    NA
  att                       geometry n.overlaps origins id
1   1 POLYGON ((1 0.5, 1 0, 0 0, ...          1       1  1
2   2 POLYGON ((0.5 1, 1 1, 1 0.5...          2    1, 2  2
3   1 POLYGON ((0.5 1, 0.5 1.5, 1...          1       2  3