reduce_space.array: Apply a function over space and bands in a four-dimensional...

In appelmar/gdalcubes_R: Earth Observation Data Cubes from Satellite Image Collections

Apply a function over space and bands in a four-dimensional (band, time, y, x) array and reduce spatial dimensions

Description

Apply a function over space and bands in a four-dimensional (band, time, y, x) array and reduce spatial dimensions

Usage

## S3 method for class 'array'
reduce_space(x, FUN, ...)

Arguments

x	four-dimensional input array with dimensions band, time, y, x (in this order)
FUN	function which receives one spatial slice in a three-dimensional array with dimensions bands, y, x as input
...	further arguments passed to FUN

Details

FUN is expected to produce a numeric vector (or scalar) where elements are interpreted as new bands in the result.

Note

This is a helper function that uses the same dimension ordering as gdalcubes streaming. It can be used to simplify the application of R functions e.g. over spatial slices in a data cube.

Examples

d <- c(4,16,32,32)
x <- array(rnorm(prod(d)), d)
# reduce individual bands over spatial slices 
y <- reduce_space(x, function(v) {
  apply(v, 1, mean)
})
dim(y)

appelmar/gdalcubes_R documentation built on March 9, 2024, 10:23 a.m.