spatstat (version 1.23-1)

Replace.im: Reset Values in Subset of Image

Description

Reset the values in a subset of a pixel image.

Usage

## S3 method for class 'im':
[(x, i) <- value

Arguments

x

A two-dimensional pixel image. An object of class "im".

i

Object defining the subregion or subset to be extracted. Either a spatial window (an object of class "owin") or a point pattern (an object of class "ppp") or something that can be converted into a point pattern by

value

Vector of replacement values (short vectors will be recycled).

Value

• The image x with the values replaced.

Details

This function changes some of the pixel values in a pixel image. The image X must be an object of class "im" representing a pixel image defined inside a rectangle in two-dimensional space (see im.object).

The subset to be changed is determined by the argument i.

If i is a spatial window (an object of class "owin"), the values of the image inside this window are changed.

If i is a point pattern (an object of class "ppp", or something that can be converted into a point pattern by as.ppp), then the values of the pixel image at the points of this pattern are changed.

If i does not satisfy any of the conditions above, then it is assumed to be a valid index for the matrix as.matrix(x).

See Also

im.object, [.im, ppp.object, as.ppp, owin.object

Examples

# make up an image
 X <- setcov(unit.square())
 plot(X)

 # a rectangular subset
 W <- owin(c(0,0.5),c(0.2,0.8))
 X[W] <- 2
 plot(X)

 # a polygonal subset
 data(letterR)
 R <- affine(letterR, diag(c(1,1)/2), c(-2,-0.7))
 X[R] <- 3
 plot(X)

 # a point pattern
 P <- rpoispp(20)
 X[P] <- 10
 plot(X)

 # change pixel value at a specific location
 X[list(x=0.1,y=0.2)] <- 7