R: Apply a function over time and bands in a four-dimensional...

reduce_time.array {gdalcubes} | R Documentation

## Apply a function over time and bands in a four-dimensional (band, time, y, x) array and reduce time dimension

### Description

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

### Usage

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

### Arguments

`x` | four-dimensional input array with dimensions band, time, y, x (in this order)
`FUN` | function which receives one time series in a two-dimensional array with dimensions bands, time 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 time series in a data cube.

### Examples

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

[Package gdalcubes version 0.3.1 Index]