lsp_transform {motif}

Transforms lsp objects

Description

It allows for transforming spatial signatures (outputs of the lsp_signature() function) using user-provided functions. See examples for more details.

Usage

lsp_transform(x, fun, ...)

Arguments

x

Object of class lsp - usually the output of the lsp_signature() function.

fun

A user-provided function.

...

Additional arguments for fun.

Value

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

Examples

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]]

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]]


# 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]]

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]]