options(digits = 3)
# data1 include distance and angle
data1$x <- data1$距离*sin(data1$角度/180*pi)
data1$y <- data1$距离*cos(data1$角度/180*pi)
#
# data1$x <- data1$X
# data1$y <- data1$Y
# data <- data1
order(data1$角度,decreasing = T)
data <- data1[order(data1$角度,decreasing = F),]
n <- nrow(data)
z1 <- numeric(n-2);z2 <- numeric(n-2);ss <- numeric(n-2)
for (i in 1:(n-2)) {
d1 <- data[c(1,i+1,i+2),c(3,4)]
zx <- mean(d1$x);zy <- mean(d1$y)
s <- 1/2*(d1$x[1]*d1$y[2]+d1$x[2]*d1$y[3]+d1$x[3]*d1$y[1]-d1$x[1]*d1$y[3]-d1$x[2]*d1$y[1]-d1$x[3]*d1$y[2])
z1 <- zx
z2 <- zy
ss <- s
}
zzx <- sum(z1*ss)/sum(ss)
zzy <- sum(z2*ss)/sum(ss)
zhongxin <- c(zzx,zzy)
zhongxin