spatstat (version 1.52-1)

areaGain: Difference of Disc Areas

Description

Computes the area of that part of a disc that is not covered by other discs.

Usage

```areaGain(u, X, r, ..., W=as.owin(X), exact=FALSE,
ngrid=spatstat.options("ngrid.disc"))```

Arguments

u

Coordinates of the centre of the disc of interest. A vector of length 2. Alternatively, a point pattern (object of class `"ppp"`).

X

Locations of the centres of other discs. A point pattern (object of class `"ppp"`).

r

Ignored.

W

Window (object of class `"owin"`) in which the area should be computed.

exact

Choice of algorithm. If `exact=TRUE`, areas are computed exactly using analytic geometry. If `exact=FALSE` then a faster algorithm is used to compute a discrete approximation to the areas.

ngrid

Integer. Number of points in the square grid used to compute the discrete approximation, when `exact=FALSE`.

Value

A matrix with one row for each point in `u` and one column for each value in `r`.

Details

This function computes the area of that part of the disc of radius `r` centred at the location `u` that is not covered by any of the discs of radius `r` centred at the points of the pattern `X`. This area is important in some calculations related to the area-interaction model `AreaInter`.

If `u` is a point pattern and `r` is a vector, the result is a matrix, with one row for each point in `u` and one column for each entry of `r`. The `[i,j]` entry in the matrix is the area of that part of the disc of radius `r[j]` centred at the location `u[i]` that is not covered by any of the discs of radius `r[j]` centred at the points of the pattern `X`.

If `W` is not `NULL`, then the areas are computed only inside the window `W`.

`AreaInter`, `areaLoss`

Examples

Run this code
``````# NOT RUN {
data(cells)
u <- c(0.5,0.5)
areaGain(u, cells, 0.1)
# }
``````

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