freq: Frequencies of cell values in a raster

In adamlilith/fasterRaster: Faster Raster and Spatial Vector Processing Using 'GRASS GIS'

Frequencies of cell values in a raster

Description

freq() tabulates the frequency of cell values in a raster. For rasters where datatype() is integer or factor, the frequency of each value or level is reported. For other rasters, the range of values is divided into bins, and the number of cells with values in each bin is reported.

Usage

## S4 method for signature 'GRaster'
freq(x, digits = 3, bins = 100, value = NULL)

Arguments

x	A GRaster.
digits	Numeric integer: Number of digits by which to round raster values. Ignored for integer and categorical rasters.
bins	Positive numeric integer: Number of bins in which to divide values of numeric rasters. The default is 100. For integer and categorical rasters, each value is tallied (i.e., this is ignored).
value	Numeric or NULL (default): If numeric, only cells with this value will be counted. If NULL, all values will be counted.

Value

A data.frame or a named list of data.frames, one per layer in x.

See Also

terra::freq(), module r.stats in GRASS

Examples

if (grassStarted()) {

# Setup
library(terra)

# Example data
madElev <- fastData("madElev") # raster
madCover <- fastData("madCover") # categorical raster

# Convert to GRasters
elev <- fast(madElev) # raster
cover <- fast(madCover) # categorical raster

# Frequencies of integer raster values
f <- freq(elev)
print(f) # have to do this sometimes if output is a data table

# Frequencies of categorical raster values
f <- freq(cover)
print(f) # have to do this sometimes if output is a data table

# Frequencies of given values
f <- freq(elev, value = 1)
print(f) # have to do this sometimes if output is a data table

# When a GRaster has non-integer values, they will be binned:
f <- freq(elev + 0.1, bins = 10)
print(f)

}

adamlilith/fasterRaster documentation built on Dec. 21, 2024, 2:04 a.m.