R: Apply Affine Transformation To Point Pattern

affine.ppp {spatstat.geom} | R Documentation

## Apply Affine Transformation To Point Pattern

### Description

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

### Usage

     ## S3 method for class '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.owin` affecting 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 * 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.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`affine`, `affine.owin`, `affine.psp`, `affine.im`, `flipxy`, `rotate`, `shift`

### Examples

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

[Package spatstat.geom version 2.2-0 Index]