问题
So after looking at various Questions asked here on stackoverflow I'm still not able to wrap my head around the dist function in R or maybe even a distance matrix in general.
So I have two dataframes with xy-coordinates.
df1 <- data.frame(x = runif(3,0,50), y = runif(3,0,50))
df2 <- data.frame(x = runif(20,0,50), y = runif(20,0,50))
I want to iterate through the first dataframe and for each point/row I want to check the distance to all the points in the second df. This is probably extremely easy to do and I am sorry and ashamed that I am asking this, but I'm trying for hours now. Any help is appreciated!
回答1:
the pakcage proxy lets you calcualte distances between rows of matrices in addition to providing many more distance metrics.
library(proxy)
df1=data.frame(x=runif(3,0,50),y=runif(3,0,50))
df2=data.frame(x=runif(20,0,50),y=runif(20,0,50))
dist(df1, df2, method = "euclidean")
# [,1] [,2] [,3]
# [1,] 14.502244 15.272563 30.266583
# [2,] 33.152003 44.574128 32.464425
# [3,] 30.112443 42.935810 12.935461
# [4,] 31.749340 38.809452 45.214138
# [5,] 22.712121 25.358099 45.593262
# [6,] 24.702575 31.332886 41.528598
# [7,] 38.244377 46.768200 46.222620
# [8,] 13.686492 1.378374 41.466495
# [9,] 30.884628 40.148856 39.286827
#[10,] 7.615178 19.138047 27.597653
#[11,] 24.898710 22.577377 51.314388
#[12,] 27.962082 39.389227 29.863587
#[13,] 26.927504 39.687474 18.898984
#[14,] 22.249277 26.451882 43.537306
#[15,] 14.632805 24.817799 30.319079
#[16,] 32.483518 41.170256 41.874111
#[17,] 16.471009 23.334594 20.552049
#[18,] 15.561002 27.706218 13.277251
#[19,] 13.375505 19.056233 24.006360
#[20,] 30.191274 42.999607 12.498551
来源：https://stackoverflow.com/questions/48117286/distance-between-two-sets-of-points