cells_from_val: Obtain a RasterLayer or the cells of RasterLayer that are...

In edwardlavender/flapper: Routines for the Analysis of Passive Acoustic Telemetry Data

Obtain a RasterLayer or the cells of RasterLayer that are equal to or lie within a range of specified values

Description

This function obtains a RasterLayer or the cells of a RasterLayer that are equal to a specified value or lie within a specified range of values. To implement this function, a raster (x) and a value or range of values (y) for which a RasterLayer or the numbers of cells corresponding to those values are desired must be supplied. If a range of values is supplied, an additional argument (interval) controls whether or not cells within and equal to or simply within the specified range are returned.

Usage

cells_from_val(x, y, interval = 1L, cells = TRUE, na.rm = TRUE)

Arguments

x	A raster object.
y	A number or a vector with two numbers representing the lower and upper boundaries of the interval of values within which cells are identified.
interval	If y is a vector of length two, interval is an integer that controls whether or not to query cells within and equal to (interval = 1L) or simply within (interval = 2L) the range specified by y.
cells	A logical variable that defines whether or not to return a vector of cell numbers (TRUE) or a RasterLayer of the cells corresponding to y.
na.rm	A logical variable that defines whether or not to ignore NAs.

Value

The function returns a RasterLayer (if cells = FALSE) or an integer vector of numbers (if cells = TRUE) that defines the cells that are equal to, or lie within, specified value(s) y.

Author(s)

Edward Lavender

Examples

# Define an example RasterLayer
ncl <- 10
nrw <- 10
n <- ncl * nrw
mat <- matrix(1:n, ncol = ncl, nrow = nrw, byrow = TRUE)
r <- raster::raster(mat)
# Visualise example RasterLayer
raster::plot(r)
raster::text(r)
# Obtain the number(s) of cells corresponding to a particular value
cells_from_val(r, 1)
# Obtain a RasterLayer of the cells corresponding to a particular value
r1 <- cells_from_val(r, 1, cells = FALSE)
raster::plot(r1)
# Obtain the number(s) of cells within or equal to a range of values
cells_from_val(r, c(1, 10))
# Obtain the number(s) of cells within a range of values
cells_from_val(r, c(1, 10), interval = 2L)
# As above but returning a raster layer
cells_from_val(r, c(1, 10), interval = 2L, cells = FALSE)

edwardlavender/flapper documentation built on Jan. 22, 2025, 2:44 p.m.