init: Initialize a SpatRaster with values

In terra: Spatial Data Analysis

Initialize a SpatRaster with values

Description

Create a SpatRaster with values reflecting a cell property: 'x', 'y', 'col', 'row', 'cell' or 'chess'. Alternatively, a function can be used. In that case, cell values are initialized without reference to pre-existing values. E.g., initialize with a random number (fun=runif). While there are more direct ways of achieving this for small objects (see examples) for which a vector with all values can be created in memory, the init function will also work for SpatRaster objects with many cells.

Usage

## S4 method for signature 'SpatRaster'
init(x, fun, filename="", ...)

Arguments

x	SpatRaster
fun	function to be applied. This must be a either single number, multiple numbers, a function, or one of a set of known character values. A function must take the number of cells as a single argument to return a vector of values with a length equal to the number of cells, such as fun=runif. Allowed character values are 'x', 'y', 'row', 'col', 'cell', and 'chess' to get the x or y coordinate, row, col or cell number or a chessboard pattern (alternating 0 and 1 values)
filename	character. Output filename
...	additional arguments for writing files as in writeRaster

Value

SpatRaster

Examples

r <- rast(ncols=10, nrows=5, xmin=0, xmax=10, ymin=0, ymax=5)
x <- init(r, fun="cell")
y <- init(r, fun=runif)

# initialize with a single value 
z <- init(r, fun=8)

terra documentation built on Oct. 13, 2023, 5:08 p.m.