frasterize: Fast rasterize

In rinnan/fraster: Fast manipulation of raster objects

Description

Expands the fasterize() function to sp compatibility.

Usage

frasterize(x, y, ...)

## S4 method for signature 'sf,Raster'
frasterize(x, y, field = NULL, fun = "last", background = NA, by = NULL)

## S4 method for signature 'Spatial,Raster'
frasterize(x, y, field = NULL, fun = "last", background = NA, by = NULL)

Arguments

x	Spatial* object from sf or sp classes
y	Raster* object
...	additional arguments (none currently implemented)
field	numeric or character. The value(s) to be transferred. This can be a single number, or a vector of numbers that has the same length as the number of spatial features (points, lines, polygons). If x is a Spatial*DataFrame, this can be the column name of the variable to be transferred. If missing, the attribute index is used (i.e. numbers from 1 to the number of features). You can also provide a vector with the same length as the number of spatial features, or a matrix where the number of rows matches the number of spatial features
fun	function or character. To determine what values to assign to cells that are covered by multiple spatial features. You can use functions such as min, max, or mean, or one of the following character values: 'first', 'last', 'count'. The default value is 'last'. In the case of SpatialLines*, 'length' is also allowed (currently for planar coordinate systems only). If x represents points, fun must accept a na.rm argument, either explicitly or through 'dots'. This means that fun=length fails, but fun=function(x,...)length(x) works, although it ignores the na.rm argument. To use the na.rm argument you can use a function like this: fun=function(x, na.rm)if (na.rm) length(na.omit(x)) else (length(x), or use a function that removes NA values in all cases, like this function to compute the number of unique values per grid cell "richness": fun=function(x, ...) length(unique(na.omit(x))) . If you want to count the number of points in each grid cell, you can use fun='count' or fun=function(x,...)length(x). You can also pass multiple functions using a statement like fun=function(x, ...) c(length(x),mean(x)), in which case the returned object is a RasterBrick (multiple layers).
background	numeric. Value to put in the cells that are not covered by any of the features of x. Default is NA
by	character. The name of a column in 'sf' by which to aggregate layers. If set, fasterize will return a RasterBrick with as many layers as unique values of the 'by' column.

Value

A raster of the same size, extent, resolution and projection as the provided raster template.

References

Wylie, C., Romney, G., Evans, D., & Erdahl, A. (1967). Half-tone perspective drawings by computer. Proceedings of the November 14-16, 1967, Fall Joint Computer Conference. AFIPS '67 (Fall). <https://dx.doi.org/10.1145/1465611.1465619>

rinnan/fraster documentation built on May 22, 2020, 11:36 p.m.