extend: Extend

In raster: Geographic Data Analysis and Modeling

Description

Extend returns an Raster* object with a larger spatial extent. The output Raster object has the outer minimum and maximum coordinates of the input Raster and Extent arguments. Thus, all of the cells of the original raster are included. See crop if you (also) want to remove rows or columns.

There is also an extend method for Extent objects to enlarge (or reduce) an Extent. You can also use algebraic notation to do that (see examples)

This function has replaced function "expand" (to avoid a name conflict with the Matrix package).

Usage

## S4 method for signature 'Raster'
extend(x, y, value=NA, filename='', ...) 

## S4 method for signature 'Extent'
extend(x, y, ...) 

Arguments

x	Raster or Extent object
y	If x is a Raster object, y should be an Extent object, or any object that is or has an Extent object, or an object from which it can be extracted (such as sp objects). Alternatively, you can provide a numeric vector of length 2 indicating the number of rows and columns that need to be added (or a single number when the number of rows and columns is equal) If x is an Extent object, y should be a numeric vector of 1, 2, or 4 elements
value	value to assign to new cells
filename	Character (optional)
...	Additional arguments as for writeRaster

Value

RasterLayer or RasterBrick, or Extent

Author(s)

Robert J. Hijmans and Etienne B. Racine (Extent method)

See Also

crop, merge

Examples

r <- raster(xmn=-150, xmx=-120, ymx=60, ymn=30, ncol=36, nrow=18)
values(r) <- 1:ncell(r)
e <- extent(-180, 0, 0, 90)
re <- extend(r, e)

# extend with a number of rows and columns (at each side)
re2 <- extend(r, c(2,10))

# Extent object
e <- extent(r)
e
extend(e, 10)
extend(e, 10, -10, 0, 20)
e + 10
e * 2

Example output

Loading required package: sp
class       : Extent 
xmin        : -150 
xmax        : -120 
ymin        : 30 
ymax        : 60 
class       : Extent 
xmin        : -160 
xmax        : -110 
ymin        : 20 
ymax        : 70 
class       : Extent 
xmin        : -160 
xmax        : -110 
ymin        : 20 
ymax        : 70 
class       : Extent 
xmin        : -155 
xmax        : -115 
ymin        : 25 
ymax        : 65 
class       : Extent 
xmin        : -165 
xmax        : -105 
ymin        : 15 
ymax        : 75 

raster documentation built on Jan. 5, 2021, 3:01 a.m.