It allows for transforming spatial signatures (outputs of
the lsp_signature() function) using user-provided functions.
See examples for more details.
lsp_transform(x, fun, ...)Object of class lsp - usually the output of
the lsp_signature() function.
A user-provided function.
Additional arguments for fun.
Object of class lsp.
It has three columns: (1) id - an id of each window.
For irregular windows, it is the values provided in the window argument,
(2) na_prop - share (0-1) of NA cells for each window,
(3) signature - a list-column containing with calculated signatures
library(stars)
landform = read_stars(system.file("raster/landforms.tif", package = "motif"))
result_coma500 = lsp_signature(landform, type = "coma", threshold = 0.5, window = 500)
#see how the first signature looks
result_coma500$signature[[1]]
#> 1 5 6 7 8 9 10 11 12 14 15 17
#> 1 214604 33 126 10 474 72 33 0 0 0 0 690
#> 5 33 296 18 0 51 0 0 0 0 0 0 1
#> 6 126 18 994 0 72 0 0 0 0 0 0 0
#> 7 10 0 0 6184 422 249 19 0 0 72 0 0
#> 8 474 51 72 422 25208 124 105 0 0 140 2 10
#> 9 72 0 0 249 124 58622 1175 776 6 26 45 6
#> 10 33 0 0 19 105 1175 24174 14 452 13 40 0
#> 11 0 0 0 0 0 776 14 33368 1368 0 0 0
#> 12 0 0 0 0 0 6 452 1368 609562 0 0 39
#> 14 0 0 0 72 140 26 13 0 0 1366 3 0
#> 15 0 0 0 0 2 45 40 0 0 3 970 0
#> 17 690 1 0 0 10 6 0 0 39 0 0 542
my_function = function(mat){
mat_c = colSums(mat)
freqs = mat_c / sum(mat)
# entropy
-sum(freqs * log2(freqs), na.rm = TRUE)
}
result_coma500_2 = lsp_transform(result_coma500, my_function)
#see how the first signature looks after transformation
result_coma500_2$signature[[1]]
#> [1] 1.712131
# \donttest{
# larger data example
library(stars)
landform = read_stars(system.file("raster/landform.tif", package = "motif"))
result_coma500 = lsp_signature(landform, type = "coma", threshold = 0.5, window = 500)
#see how the first signature looks
result_coma500$signature[[1]]
#> 1 2 3 4 5 6 7 8 9 10 11 12 13 14
#> 1 126136 244 91 577 10 641 640 472 19 0 22 0 0 0
#> 2 244 2292 60 30 0 3 0 0 0 0 26 0 0 0
#> 3 91 60 7182 418 0 196 0 0 0 0 68 0 0 0
#> 4 577 30 418 19010 0 483 2 1 0 0 173 0 0 0
#> 5 10 0 0 0 9760 810 271 27 0 0 0 261 1 0
#> 6 641 3 196 483 810 86384 536 552 0 0 5 911 61 0
#> 7 640 0 0 2 271 536 76198 2474 177 52 0 58 303 0
#> 8 472 0 0 1 27 552 2474 81192 0 164 0 60 926 0
#> 9 19 0 0 0 0 0 177 0 5728 309 0 0 0 0
#> 10 0 0 0 0 0 0 52 164 309 36566 0 0 0 0
#> 11 22 26 68 173 0 5 0 0 0 0 1256 0 0 0
#> 12 0 0 0 0 261 911 58 60 0 0 0 12310 237 0
#> 13 0 0 0 0 1 61 303 926 0 0 0 237 26508 0
#> 14 0 0 0 0 0 0 0 0 0 0 0 0 0 0
#> 15 904 0 0 38 0 136 10 41 0 0 0 0 0 0
#> 15
#> 1 904
#> 2 0
#> 3 0
#> 4 38
#> 5 0
#> 6 136
#> 7 10
#> 8 41
#> 9 0
#> 10 0
#> 11 0
#> 12 0
#> 13 0
#> 14 0
#> 15 894
my_function = function(mat){
mat_c = colSums(mat)
freqs = mat_c / sum(mat)
# entropy
-sum(freqs * log2(freqs), na.rm = TRUE)
}
result_coma500_2 = lsp_transform(result_coma500, my_function)
#see how the first signature looks after transformation
result_coma500_2$signature[[1]]
#> [1] 2.996814
# }