shift.ppp {spatstat.geom}

Apply Vector Translation To Point Pattern

Description

Applies a vector shift to a point pattern.

Usage

 ## S3 method for class 'ppp'
shift(X, vec=c(0,0), ..., origin=NULL)

Arguments

X

Point pattern (object of class "ppp").

vec

Vector of length 2 representing a translation.

...

Ignored

origin

Location that will be shifted to the origin. Either a numeric vector of length 2 giving the location, or a point pattern containing only one point, or a list with two entries named x and y, or one of the character strings "centroid", "midpoint", "left", "right", "top", "bottom", "topleft", "bottomleft", "topright" or "bottomright" (partially matched).

Details

The point pattern, and its window, are translated by the vector vec.

This is a method for the generic function shift.

If origin is given, the argument vec will be ignored; instead the shift will be performed so that the specified geometric location is shifted to the coordinate origin (0,0). The argument origin should be either a numeric vector of length 2 giving the spatial coordinates of a location, or one of the character strings "centroid", "midpoint", "left", "right", "top", "bottom", "topleft", "bottomleft", "topright" or "bottomright" (partially matched). If origin="centroid" then the centroid of the window will be shifted to the origin. If origin="midpoint" then the centre of the bounding rectangle of the window will be shifted to the origin. If origin="bottomleft" then the bottom left corner of the bounding rectangle of the window will be shifted to the origin, and so on.

Value

Another point pattern (of class "ppp") representing the result of applying the vector shift.

Author(s)

Adrian Baddeley [e-mail] and Rolf Turner [e-mail]

See Also

shift, shift.owin, periodify, rotate, affine

Examples

  X <- shift(cells, c(2,3))
  # plot(X)
  # no discernible difference except coordinates are different
  plot(cells, pch=16)
  plot(shift(cells, c(0.03,0.03)), add=TRUE)

  shift(cells, origin="mid")