问题
I have a SpatialLinesDataFrame with streets and I have a list of GPS coordinates. What I need to do is to get out the 10 closest street names for each individual GPS coordinate.
Is there a function/package in R that would calculate the distance between a line and a point for a SpatialLinesDataFrame? I can't see anything that would help in 'sp'.
There is a related question: Calculating the distance between polygon and point in R, but I want to find the distance between a line object and a point, not polygon/point, point/point.
回答1:
You could use rgeos::gDistance() with byid=TRUE to get a matrix of distances from each point to each line. From there, it's relatively easy to extract the ids of the 10 lines nearest to each point:
library(sp)
library(rgeos)
## Create a SpatialPoints and a SpatialLines object
example("SpatialPoints-class", ask=FALSE, echo=FALSE)
example("SpatialLines-class", ask=FALSE, echo=FALSE)
## Compute the matrix of distances between them.
(m <- gDistance(S, Sl, byid=TRUE))
# 1 2 3 4 5
# a 0.000000 0.0 2.757716 1.414214 2.757716
# b 1.788854 0.5 3.640055 1.000000 3.605551
## And then use it to extract the ids of the 10 (or in this case 1) lines
## closest to each point.
## apply(m, 2, function(X) rownames(m)[order(X)][1:10]) ## Finds 10 closest
apply(m, 2, function(X) rownames(m)[order(X)][1]) ## Finds single closest
# 1 2 3 4 5
# "a" "a" "a" "b" "a"
来源：https://stackoverflow.com/questions/19126998/spatiallinesdataframe-how-to-calculate-the-min-distance-between-a-point-and-a