I want to replace the values of a given row of a SpatRaster x with the values of a given row of SpatRaster y:
Example data:
library(terra)
r <- rast( extent=c( -108, -105, 39, 42 ), ncol=14, nrow=14, crs="epsg:4326" )
values(r) <- 1:ncell(r)
x <- c(r, r*2, r*3, r*0.5)
x
#class : SpatRaster
#dimensions : 14, 14, 4 (nrow, ncol, nlyr)
#resolution : 0.2142857, 0.2142857 (x, y)
#extent : -108, -105, 39, 42 (xmin, xmax, ymin, ymax)
#coord. ref. : lon/lat WGS 84 (EPSG:4326)
#sources : memory
# memory
# memory
# ... and 1 more source(s)
#names : lyr.1, lyr.1, lyr.1, lyr.1
#min values : 1.0, 2.0, 3.0, 0.5
#max values : 196, 392, 588, 98
y <- x
values(y) <- 5
I try to replace 1 row of x with 1 row of y using values()
x[1,,,,drop=FALSE]
#class : SpatRaster
#dimensions : 1, 14, 4 (nrow, ncol, nlyr)
#resolution : 0.2142857, 0.2142857 (x, y)
#extent : -108, -105, 41.78571, 42 (xmin, xmax, ymin, ymax)
#coord. ref. : lon/lat WGS 84 (EPSG:4326)
#source : memory
#names : lyr.1, lyr.1, lyr.1, lyr.1
#min values : 1.0, 2.0, 3.0, 0.5
#max values : 14, 28, 42, 7
y[1,,,,drop=FALSE]
#class : SpatRaster
#dimensions : 1, 14, 4 (nrow, ncol, nlyr)
#resolution : 0.2142857, 0.2142857 (x, y)
#extent : -108, -105, 41.78571, 42 (xmin, xmax, ymin, ymax)
#coord. ref. : lon/lat WGS 84 (EPSG:4326)
#source : memory
#names : lyr.1, lyr.1, lyr.1, lyr.1
#min values : 5, 5, 5, 5
#max values : 5, 5, 5, 5
values(x[1,,,,drop=FALSE]) |> head(3)
# lyr.1 lyr.1 lyr.1 lyr.1
#[1,] 1 2 3 0.5
#[2,] 2 4 6 1.0
#[3,] 3 6 9 1.5
values(y[1,,,,drop=FALSE]) |> head(3)
lyr.1 lyr.1 lyr.1 lyr.1
#[1,] 5 5 5 5
#[2,] 5 5 5 5
#[3,] 5 5 5 5
But the following does not work:
> values(x[1,,,,drop=FALSE]) <- values(y[1,,,,drop=FALSE])
Error in .local(x, i, j = j, ..., value) :
unused arguments (alist(, drop = FALSE, value))
Why this error? Note that the following works:
x1 <- x[1,,,,drop=FALSE]
y1 <- y[1,,,,drop=FALSE]
values(x1) <- values(y1)
but I need to replace row values within x. Any solution or alternative?
You should not use drop=FALSE in this case, and only one comma.
x[1,] |> head(3)
# lyr.1 lyr.1.1 lyr.1.2 lyr.1.3
#1 1 2 3 0.5
#2 2 4 6 1.0
#3 3 6 9 1.5
x[1,] <- y[1,]
x[1,] |> head(3)
# lyr.1 lyr.1.1 lyr.1.2 lyr.1.3
#1 5 5 5 5
#2 5 5 5 5
#3 5 5 5 5