Compute "rolling" or "moving" values, such as the "rolling average" for each cell in a SpatRaster.
See focal for spatially moving averages and similar computations. And see cumsum and other cum* functions to compute cumulate values.
# S4 method for SpatRaster
roll(x, n, fun=mean, type="around", circular=FALSE,
na.rm=FALSE, filename="", ..., wopt=list()) # S4 method for numeric
roll(x, n, fun=mean, type="around", circular=FALSE, na.rm=FALSE, ...)
Same as x
SpatRaster or numeric
integer > 1. The size of the "window", that is, the number of sequential cells to use in fun
a function like mean, min, max, sum
character. One of "around", "to", or "from". The choice indicates which values should be used in the computation. The focal cell is always used. If type is "around", (n-1)/2 before and after the focal cell are also included. If type = "from", n-1 cells are after the focal cell are included. If type = "to", n-1 cells before the focal cell are included. For example, when using n=3 for element 5 of a vector; "around" used elements 4,5,6; "to" used elements 3,4,5, and "from" uses elements 5,6,7
logical. If TRUE, the data are considered to have a circular nature (e.g. days or months of the year), such that there are no missing values before first or after the last value.
logical. If TRUE, NA values should be ignored (by fun)
character. Output filename
additional arguments for fun
list with named options for writing files as in writeRaster
cumsum, focal
## numeric
roll(1:12, 3, mean)
roll(1:12, 3, mean, "to")
roll(1:12, 3, mean, circular=TRUE)
## SpatRaster
r <- rast(ncol=2, nrow=2, nlyr=10, vals=1)
r[1,2] <- 2
r[2,2] <- 4
values(roll(r, n=3, "sum", "from", na.rm=FALSE))
values(roll(r, n=3, "sum", "from", na.rm=TRUE))
values(roll(r, n=3, "sum", "from", circular=TRUE))
values(roll(r, n=3, "sum", "to", na.rm=TRUE))
values(roll(r, n=3, "sum", "around", circular=TRUE))
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