rReduce: Combine a raster stack after segregation
In EhrmannS/rasterTools: Obtain and process earth observation data

Description Usage Arguments Details Value See Also Examples

Successively combine the layers of a raster stack with each other (similar to Reduce).

1 2	rReduce(obj, by = NULL, fun = function(x) sum(x, na.rm = TRUE), weights = NULL, direction = "right")

`obj`	[`RasterLayer(1)`] The object to modify.
`by`	[`list(.)`] the cell values by which the layers shall be aggregated; see Details.
`fun`	[`function(1)`] find the resulting value of the combined layers.
`weights`	[`numeric(length(obj))`] weight by which the values in each layer are multiplied before applying `fun`.
`direction`	[`character(1)`] the direction into which the `RasterLayer` in `obj` is supposed to be combine. Either `"right"` (default) or `"left"`; see Details.

The argument direction takes the direction into which the layers should be combined. "right" means that layers are combined from left to right. rReduce is based on the functional Reduce, where this wording is handled differently.

The number of layers in the aggregated raster depends on the length of the list in by. If by is left empty, everything is written into one RasterLayer object. Values to be aggregated in a RasterLayer are in the same list element.

a RasterLayer or RasterStack of the same dimensions as obj, in which the layers of obj are aggregated into a smaller set of layers.

Other operators to modify a raster: rBlend, rRescale, rSegregate

input <- rtRasters$continuous
patches <- rPatches(rBinarise(input, thresh = 30))
myPatches <- rSegregate(patches)

# revert the segregation
visualise(rReduce(myPatches))

# group patches
twoGroups <- list(c(1:14), c(15:28))
visualise(rReduce(myPatches, by = twoGroups))

# select a subset of patches
someLayers <- list(c(1, 3, 5, 7, 9))
visualise(rReduce(myPatches, by = someLayers))