R: Apply a function over pixel time series in a four-dimensional...

apply_time.array {gdalcubes} | R Documentation

## Apply a function over pixel time series in a four-dimensional (band, time, y, x) array

### Description

Apply a function over pixel time series in a four-dimensional (band, time, y, x) array

### Usage

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

### Arguments

`x` | four-dimensional input array with dimensions band, time, y, x (in this order)
`FUN` | function that receives a vector of band values in a one-dimensional array
`...` | further arguments passed to FUN

### Details

FUN is expected to produce a matrix (or vector if result has only one band) where rows are interpreted as new bands and columns represent time.

### Note

This is a helper function that uses the same dimension ordering as gdalcubes. 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)
    z <- apply_time(x, function(v) {
      y = matrix(NA, ncol=ncol(v), nrow=2)
      y[1,] = (v[1,] + v[2,]) / 2
      y[2,] = (v[3,] + v[4,]) / 2
      y
    })
    dim(z)

[Package gdalcubes version 0.3.1 Index]