affine.ppp
Apply Affine Transformation To Point Pattern
Applies any affine transformation of the plane (linear transformation plus vector shift) to a point pattern.
Usage
# S3 method for ppp
affine(X, mat=diag(c(1,1)), vec=c(0,0), …)Arguments
- X
Point pattern (object of class
"ppp").- mat
Matrix representing a linear transformation.
- vec
Vector of length 2 representing a translation.
- …
Arguments passed to
affine.owinaffecting the handling of the observation window, if it is a binary pixel mask.
Details
The point pattern, and its window, are subjected first to the
linear transformation represented by
mat (multiplying on the left by mat),
and are then translated by the vector vec.
The argument mat must be a nonsingular \(2 \times 2\)
matrix.
This is a method for the generic function affine.
Value
Another point pattern (of class "ppp") representing the
result of applying the affine transformation.
See Also
affine,
affine.owin,
affine.psp,
affine.im,
flipxy,
rotate,
shift
Examples
# NOT RUN {
data(cells)
# shear transformation
X <- affine(cells, matrix(c(1,0,0.6,1),ncol=2))
# }
# NOT RUN {
plot(X)
# rescale y coordinates by factor 1.3
plot(affine(cells, diag(c(1,1.3))))
# }