# affine.ppp: Apply Affine Transformation To Point Pattern

## Description

Applies any affine transformation of the plane (linear transformation
plus vector shift) to a point pattern.## Usage

affine.ppp(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.

## Value

- Another point pattern (of class
`"ppp"`

) representing the
result of applying the affine transformation.

## 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`

.

## Examples

library(spatstat)
data(cells)
# shear transformation
X <- affine(cells, matrix(c(1,0,0.6,1),ncol=2))
plot(X)
# rescale y coordinates by factor 1.3
plot(affine(cells, diag(c(1,1.3))))