计算多个记录以匹配行的两点之间的距离-循环遍历两个矩阵的行

Question

I have got two matrices with coordinates and I am trying to compute distances between points in matching rows, ie between row 1 in first matrix and row 1 in second matrix.

What I am getting is computed distance between row 1 and all the other rows. This is creating memory issues as I have 800,000 rows. Does anyone know how to ask for that?

I am using

dist1 <- distm(FareStageMatrix[1:25000,], LSOACentroidMatrix[1:25000,], fun=distHaversine)

I am trying to create something like this but doesn't seem to work

for(i in 1:nrow(FareStageMatrix)) {
    for(j in 1:nrow(LSOACentroidMatrix)) {
        my_matrix[i] <- my_matrix[distm(FareStageMatrix[i], LSOACentroidMatrix[i], fun=distHaversine)]
    }
}

changed to

for (i in 1:nrow(FareStageMatrix)){
    for (i in 1:nrow(LSOACentroidMatrix)){
      r1<-FareStageMatrix[i,]
      r2<-LSOACentroidMatrix[i,]
      results[i]<-distm(r1, r2, fun=distHaversine)  
}
}

Is that something that should be working?

Answer 1

It seems I have managed to find a solution to that:

results<-matrix(NA,nrow(FareStageMatrix))

for (i in 1:nrow(FareStageMatrix)){
  for (i in 1:nrow(LSOACentroidMatrix)){
    r1<-FareStageMatrix[i,]
    r2<-LSOACentroidMatrix[i,]
    results[i]<-distm(r1, r2, fun=distHaversine)  ## Example function
  }
}

where FareStageMatrix and LSOACentroidMatrix are matrices with coordinates

It seems to have calculated one distance for a given pair of points

Answer 2

I've adapted geosphere 's distGeo function (geodesic distance) for this purpose.

library(geosphere)
source("https://raw.githubusercontent.com/RomanAbashin/distGeo_v/master/distGeo_v.R")

Data

set.seed(1702)

m1 <- matrix(runif(20000, -10, 10), ncol = 2) 
m2 <- matrix(runif(20000, -10, 10), ncol = 2)

Code

result <- distGeo_v(m1[, 1], m1[, 2], 
                    m2[, 1], m2[, 2])

Result

> head(m1)
          [,1]      [,2]
[1,]  8.087152  9.227607
[2,]  9.528334  9.103403
[3,]  5.637921 -2.213228
[4,] -2.473758 -9.812986
[5,] -2.844036 -5.245779
[6,] -4.824615 -4.330890

> head(m2)
           [,1]       [,2]
[1,]  0.1673027  0.6483745
[2,] -2.5033184  0.1386050
[3,]  4.8589785  5.1996968
[4,]  8.3239454 -8.9810949
[5,]  0.8280422 -7.8272613
[6,] -6.2633738 -5.8725562

> head(result)
[1] 1292351.3 1661739.3  824260.0 1189476.4  496403.2  233480.2