Number of immediate adjacent cells flowing into each cell
NIPD.RdCompute the number of immediate adjacent cells flowing into each cell
Arguments
- x
SpatRaster with flow-direction. see
terrain- filename
character. Output filename
- ...
additional arguments for writing files as in
writeRaster
References
Zhou, G., Wei, H. & Fu, S. A fast and simple algorithm for calculating flow accumulation matrices from raster digital elevation. Front. Earth Sci. 13, 317–326 (2019). https://doi.org/10.1007/s11707-018-0725-9 https://link.springer.com/article/10.1007/s11707-018-0725-9
Examples
elev1 <- array(NA,c(9,9))
elev2 <- elev1
dx <- 1
dy <- 1
for (r in 1:nrow(elev1)) {
y <- (r-5)*dx
for (c in 1:ncol(elev1)) {
x <- (c-5)*dy
elev1[r,c] <- 5*(x^2+y^2)
elev2[r,c] <- 10+5*(abs(x))-0.001*y ### 5*(x^2+y^2)
}
}
## Elevation Raster
elev1 <- rast(elev1)
elev2 <- rast(elev2)
t(array(elev1[],rev(dim(elev1)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 160 125 100 85 80 85 100 125 160
#> [2,] 125 90 65 50 45 50 65 90 125
#> [3,] 100 65 40 25 20 25 40 65 100
#> [4,] 85 50 25 10 5 10 25 50 85
#> [5,] 80 45 20 5 0 5 20 45 80
#> [6,] 85 50 25 10 5 10 25 50 85
#> [7,] 100 65 40 25 20 25 40 65 100
#> [8,] 125 90 65 50 45 50 65 90 125
#> [9,] 160 125 100 85 80 85 100 125 160
t(array(elev2[],rev(dim(elev2)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 30.004 25.004 20.004 15.004 10.004 15.004 20.004 25.004 30.004
#> [2,] 30.003 25.003 20.003 15.003 10.003 15.003 20.003 25.003 30.003
#> [3,] 30.002 25.002 20.002 15.002 10.002 15.002 20.002 25.002 30.002
#> [4,] 30.001 25.001 20.001 15.001 10.001 15.001 20.001 25.001 30.001
#> [5,] 30.000 25.000 20.000 15.000 10.000 15.000 20.000 25.000 30.000
#> [6,] 29.999 24.999 19.999 14.999 9.999 14.999 19.999 24.999 29.999
#> [7,] 29.998 24.998 19.998 14.998 9.998 14.998 19.998 24.998 29.998
#> [8,] 29.997 24.997 19.997 14.997 9.997 14.997 19.997 24.997 29.997
#> [9,] 29.996 24.996 19.996 14.996 9.996 14.996 19.996 24.996 29.996
plot(elev1)
plot(elev2)
## Flow Direction Raster
flowdir1<- terrain(elev1,v="flowdir")
flowdir2<- terrain(elev2,v="flowdir")
t(array(flowdir1[],rev(dim(flowdir1)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 2 2 2 4 4 4 8 8 8
#> [2,] 2 2 2 4 4 4 8 8 8
#> [3,] 2 2 2 4 4 4 8 8 8
#> [4,] 1 1 1 2 4 8 16 16 16
#> [5,] 1 1 1 1 0 16 16 16 16
#> [6,] 1 1 1 128 64 32 16 16 16
#> [7,] 128 128 128 64 64 64 32 32 32
#> [8,] 128 128 128 64 64 64 32 32 32
#> [9,] 128 128 128 64 64 64 32 32 32
t(array(flowdir2[],rev(dim(flowdir2)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 1 1 1 1 4 16 16 16 16
#> [2,] 1 1 1 1 4 16 16 16 16
#> [3,] 1 1 1 1 4 16 16 16 16
#> [4,] 1 1 1 1 4 16 16 16 16
#> [5,] 1 1 1 1 4 16 16 16 16
#> [6,] 1 1 1 1 4 16 16 16 16
#> [7,] 1 1 1 1 4 16 16 16 16
#> [8,] 1 1 1 1 4 16 16 16 16
#> [9,] 1 1 1 1 0 16 16 16 16
plot(flowdir1)
plot(flowdir2)
##
nidp1 <- NIDP((flowdir1))
nidp2 <- NIDP((flowdir2))
t(array(nidp1[],rev(dim(nidp1)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 0 0 0 0 0 0 0 0 0
#> [2,] 0 1 1 2 1 2 1 1 0
#> [3,] 0 1 1 2 1 2 1 1 0
#> [4,] 0 2 2 3 1 3 2 2 0
#> [5,] 0 1 1 1 9 1 1 1 0
#> [6,] 0 2 2 3 1 3 2 2 0
#> [7,] 0 1 1 2 1 2 1 1 0
#> [8,] 0 1 1 2 1 2 1 1 0
#> [9,] 0 0 0 0 0 0 0 0 0
t(array(nidp2[],rev(dim(nidp2)[1:2])))
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
#> [1,] 0 1 1 1 2 1 1 1 0
#> [2,] 0 1 1 1 3 1 1 1 0
#> [3,] 0 1 1 1 3 1 1 1 0
#> [4,] 0 1 1 1 3 1 1 1 0
#> [5,] 0 1 1 1 3 1 1 1 0
#> [6,] 0 1 1 1 3 1 1 1 0
#> [7,] 0 1 1 1 3 1 1 1 0
#> [8,] 0 1 1 1 3 1 1 1 0
#> [9,] 0 1 1 1 4 1 1 1 0
plot(nidp1)
plot(nidp2)
