识别散点图中的重叠点

Question

是否有一种简单的方法来识别包含在红色以及蓝色多边形（即绿色多边形）相交内的d1以及d2的点。

graphics.off() 
set.seed(42) 

#DATA 
d1 = data.frame(x = rnorm(20,6,2), y = rnorm(20,5,1)) 
d2 = data.frame(x = rnorm(20,8.5,1), y = rnorm(20,6,1.5)) 
ind1 = chull(d1) 
ind2 = chull(d2) 
p1 = data.frame(PID = rep(1, length(ind1)), POS = seq_along(ind1), X = d1$x[ind1], Y = d1$y[ind1]) 
p2 = data.frame(PID = rep(1, length(ind2)), POS = seq_along(ind2), X = d2$x[ind2], Y = d2$y[ind2]) 
#library(PBSmapping) 
#p3 = joinPolys(p1, p2) 
p3 = structure(list(PID = c(1L, 1L, 1L, 1L, 1L), POS = 1:5, X = c(9.19051041605104, 
9.69947043508479, 6.94793595066407, 5.50690991684707, 8.73369696007428 
), Y = c(4.69045214195459, 5.98112560649435, 6.85111759082941, 
4.67133555388548, 4.3553412183288)), .Names = c("PID", "POS", 
"X", "Y"), row.names = 0:4, class = c("PolySet", "data.frame")) 

#PLOT 
plot(x = c(d1$x,d2$x), y = c(d1$y, d2$y), type = "n", asp = 1) 
points(d1$x, d1$y, pch = 19, col = "red") 
points(d2$x, d2$y, pch = 19, col = "blue") 
polygon(p1$X, p1$Y, border = "red") 
polygon(p2$X, p2$Y, border = "blue") 
polygon(p3$X, p3$Y, border = "green", lwd = 2) 

Answer 1

的SP包有一个函数point.in.polygon，做的伎俩

library(sp) 
In1 = which(point.in.polygon(d1$x, d1$y, p3$X, p3$Y) != 0) 
points(d1$x[In1], d1$y[In1], pch = 19, col = "orange") 
In2 = which(point.in.polygon(d2$x, d2$y, p3$X, p3$Y) != 0) 
points(d2$x[In2], d2$y[In2], pch = 19, col = "orange") 

Answer 2

基于李哲源李宋哲元的评论：

library(mgcv) 
ind1_intersect = in.out(as.matrix(p3[,-(1:2)]), as.matrix(d1)) 
ind2_intersect = in.out(as.matrix(p3[,-(1:2)]), as.matrix(d2)) 

points(d1[ind1_intersect,], col = "black", pch = 19, cex = 2) 
points(d2[ind2_intersect,], col = "black", pch = 19, cex = 2)