R: Intensity Estimates Using Quadrat Counts

intensity.quadratcount {spatstat} | R Documentation

## Intensity Estimates Using Quadrat Counts

### Description

Uses quadrat count data to estimate the intensity of a point pattern in each tile of a tessellation, assuming the intensity is constant in each tile.

### Usage

    ## S3 method for class 'quadratcount'
    intensity(X, ..., image=FALSE)

### Arguments

`X` | An object of class `"quadratcount"`.
`image` | Logical value specifying whether to return a table of estimated intensities (the default) or a pixel image of the estimated intensity (`image=TRUE`).
`...` | Arguments passed to `as.mask` to determine the resolution of the pixel image, if `image=TRUE`.

### Details

This is a method for the generic function `intensity`. It computes an estimate of the intensity of a point pattern from its quadrat counts.

The argument `X` should be an object of class `"quadratcount"`. It would have been obtained by applying the function `quadratcount` to a point pattern (object of class `"ppp"`). It contains the counts of the numbers of points of the point pattern falling in each tile of a tessellation.

Using this information, `intensity.quadratcount` divides the quadrat counts by the tile areas, yielding the average density of points per unit area in each tile of the tessellation.

If `image=FALSE` (the default), these intensity values are returned in a contingency table. Cells of the contingency table correspond to tiles of the tessellation.

If `image=TRUE`, the estimated intensity function is returned as a pixel image. For each pixel, the pixel value is the estimated intensity in the tile which contains that pixel.

### Value

If `image=FALSE` (the default), a contingency table. If `image=TRUE`, a pixel image (object of class `"im"`).

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

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

### See Also

`intensity`, `quadratcount`

### Examples

      qa <- quadratcount(swedishpines, 4,3)
      qa
      intensity(qa)
      plot(intensity(qa, image=TRUE))

[Package spatstat version 1.63-3 Index]