subsDT: Speedy Raster Value Substitution

In rasterDT: Fast Raster Summary and Manipulation

Speedy Raster Value Substitution

Description

A fast data.table-based alternative to raster::subs().

Usage

subsDT(x, dict, by = 1, which = 2, subsWithNA = TRUE, filename = "", ...)

Arguments

x	Categorical RasterLayer with integer values giving field class.
dict	A data.frame or data.table with one (or possibly more) columns corresponding to the values of cells in x and one (or possibly more) columns giving the value to which each value in x should be mapped.
by	Vector of one or possibly more integers or character strings giving the indices or names of the column in dict containing the categorical values in x.
which	Vector of one or possibly more integers or character strings giving the indices or names of the column in dict with the numerical values to which each value in by should be mapped.
subsWithNA	Logical. If TRUE values that are not matched become NA. If FALSE, they retain their original value (which could also be NA). This latter option is handy when you want to replace only one or a few values. It cannot be used when x has multiple layers
filename	Character string giving (optional) file name to which the resultant raster should be written.
...	Additional arguments as for raster::writeRaster(), on which this function relies.

Value

A RasterLayer object.

Author(s)

Joshua O'Brien

Examples

r <- raster(ncol = 10, nrow = 10)
r[] <- round(runif(ncell(r)) * 10)
df <- data.frame(id = 2:8, v = c(10, 10, 11, 11, 12:14))
x <- subsDT(r, df)
x2 <- subsDT(r, df, subsWithNA = FALSE)

df$v2 <- df$v * 10
x3 <- subsDT(r, df, which = 2:3)

s <- stack(r, r*3)
names(s) <- c("first", "second")
x4 <- subsDT(s, df)
x5 <- subsDT(s, df, which = 2:3)

rasterDT documentation built on Dec. 28, 2022, 1:57 a.m.