Reset Values in Subset of Image
Reset the values in a subset of a pixel image.
## S3 method for class 'im': [(x, i) <- value
- A two-dimensional pixel image.
An object of class
- 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
- Vector of replacement values (short vectors will be recycled).
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
The subset to be changed is determined by the argument
i is a spatial window (an object of class
the values of the image inside this window are changed.
i is a point pattern (an object of class
"ppp", or something that can be converted into a point pattern
as.ppp), then the values of the pixel image at the points of
this pattern are changed.
i does not satisfy any of the conditions above,
then it is assumed to be a valid index for
- The image
xwith the values replaced.
# 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