as.im {spatstat}R Documentation

Convert to Pixel Image

Description

Converts various kinds of data to a pixel image

Usage

  as.im(X, ...)
  ## S3 method for class 'im'
as.im(X, W=NULL, ...,
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL)
  ## S3 method for class 'owin'
as.im(X, W=NULL, ...,
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL, value=1)
  ## S3 method for class 'matrix'
as.im(X, W=NULL, ...)
  ## S3 method for class 'tess'
as.im(X, W=NULL, ..., 
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL)
  ## S3 method for class 'function'
as.im(X, W=NULL, ...,
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL)
  ## S3 method for class 'distfun'
as.im(X, W=NULL, ...,
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL)
  ## S3 method for class 'leverage.ppm'
as.im(X, ...)
  ## Default S3 method:
as.im(X, W=NULL, ...,
        eps=NULL, dimyx=NULL, xy=NULL,
        na.replace=NULL)

Arguments

X

Data to be converted to a pixel image.

W

Window object which determines the spatial domain and pixel array geometry.

...

Additional arguments passed to X when X is a function.

eps,dimyx,xy

Optional parameters passed to as.mask which determine the pixel array geometry. See as.mask.

na.replace

Optional value to replace NA entries in the output image.

value

Optional. The value to be assigned to pixels inside the window, if X is a window.

Details

This function converts the data X into a pixel image object of class "im" (see im.object). The function as.im is generic, with methods for the classes listed above.

Currently X may be any of the following:

The spatial domain (enclosing rectangle) of the pixel image is determined by the argument W. If W is absent, the spatial domain is determined by X. When X is a function, a matrix, or a single numerical value, W is required.

The pixel array dimensions of the final resulting image are determined by (in priority order)

Note that if eps, dimyx or xy is given, this will override the pixel dimensions of X if it has them. Thus, as.im can be used to change an image's pixel dimensions.

If the argument na.replace is given, then all NA entries in the image will be replaced by this value. The resulting image is then defined everwhere on the full rectangular domain, instead of a smaller window. Here na.replace should be a single value, of the same type as the other entries in the image.

Value

An image object of class "im".

Author(s)

Adrian Baddeley Adrian.Baddeley@csiro.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz

See Also

Separate documentation for as.im.ppp

Examples

  data(demopat)
  # window object
  W <- demopat$window
  plot(W)
  Z <- as.im(W)
  image(Z)
  # function
  Z <- as.im(function(x,y) {x^2 + y^2}, unit.square())
  image(Z)
  # function with extra arguments
  f <- function(x, y, x0, y0) {
      sqrt((x - x0)^2 + (y-y0)^2)
  }
  Z <- as.im(f, unit.square(), x0=0.5, y0=0.5)
  image(Z)
  # Revisit the Sixties
  data(letterR)
  Z <- as.im(f, letterR, x0=2.5, y0=2)
  image(Z)
  # usual convention in S
  stuff <- list(x=1:10, y=1:10, z=matrix(1:100, nrow=10))
  Z <- as.im(stuff)
  # convert to finer grid
  Z <- as.im(Z, dimyx=256)

  # pixellate the Dirichlet tessellation
  Di <- dirichlet(runifpoint(10))
  plot(as.im(Di))
  plot(Di, add=TRUE)

[Package spatstat version 1.25-3 Index]