affine

From spatstat v1.9-1 by Adrian Baddeley

Apply Affine Transformation

Applies any affine transformation of the plane (linear transformation plus vector shift) to a plane geometrical object, such as a point pattern or a window.

Keywords: spatial, math

Usage

affine(X, mat=diag(c(1,1)), vec=c(0,0))

Arguments

X: Any suitable dataset representing a two-dimensional object, such as a point pattern (object of class "ppp"), or a window (object of class "owin").
mat: Matrix representing a linear transformation.
vec: Vector of length 2 representing a translation.

Details

This is generic. Methods are provided for point patterns (affine.ppp) and windows (affine.owin).

First the linear transformation represented by mat is applied (multiplying on the left by mat), and then the result is translated by the vector vec. The argument mat must be a nonsingular $2 \times 2$ matrix.

Value

Another object of the same type, representing the result of applying the affine transformation.

synopsis

affine(X, ...)

Examples

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))))

Documentation reproduced from package spatstat, version 1.9-1, License: GPL version 2 or newer

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