逆距离加权：spDists(s0, s) 中的错误：ncol(x) == ncol(y) 在 package gstat 中不是 TRUE

Question

I wish to do some "simple" inverse distance weighing. In the past I have used the idw function in gstat but that stopped working. I found an equivalent idw0 in the same package but I can not get that to work. This example code should produce 50 estimates for z-hat at the 50 points in the unknown.df data frame.

library(gstat)

set.seed(1)
x<-runif(100,0,1)
y<-runif(100,0,1)
z<-runif(100,0,1)
known.df<-data.frame(x,y,z)

x<-runif(50,0,1)
y<-runif(50,0,1)
unknown.df<-data.frame(x,y)

idw<-idw0(z~1,known.df,unknown.df)
idw<-idw0(z~1,known.df,unknown.df,y=as.matrix(known.df$z))

This produces the errors

> idw<-idw0(z~1,known.df,unknown.df)
Error in spDists(s0, s) : ncol(x) == ncol(y) is not TRUE
> idw<-idw0(z~1,known.df,unknown.df,y=as.matrix(known.df$z))
Error in spDists(s0, s) : ncol(x) == ncol(y) is not TRUE

Y has length 50, but what is x?

Answer 1

Need to explicitly denote the coordinate fields.

library(gstat)
library(sp)

set.seed(1)
x<-runif(100,0,1)
y<-runif(100,0,1)
z<-runif(100,0,1)
known.df<-data.frame(x,y,z)
coordinates(known.df) = ~ x + y

x<-runif(50,0,1)
y<-runif(50,0,1)
unknown.df<-data.frame(x,y)
coordinates(unknown.df) = ~ x + y

idw<-idw0(z~1,known.df,unknown.df)