# discpartarea

##### Area of Part of Disc

Compute area of intersection between a disc and a window

##### Usage

`discpartarea(X, r, W=as.owin(X))`

##### Arguments

- X
- Point pattern (object of class
`"ppp"`

) specifying the centres of the discs. Alternatively,`X`

may be in any format acceptable to`as.ppp`

. - r
- Matrix, vector or numeric value specifying the radii of the discs.
- W
- Window (object of class
`"owin"`

) with which the discs should be intersected.

##### Details

This algorithm computes the exact area of the intersection between
a window `W`

and a disc (or each of several discs).
The centres of the discs are specified by the point pattern
`X`

, and their radii are specified by `r`

.

If `r`

is a single numeric value, then the algorithm computes the
area of intersection between `W`

and the disc of radius `r`

centred
at each point of `X`

, and returns a one-column matrix
containing one entry for each point of `X`

.

If `r`

is a vector of length `m`

, then the algorithm
returns an `n * m`

matrix in which the entry on row `i`

,
column `j`

is the area of the
intersection between `W`

and the disc centred at `X[i]`

with radius `r[j]`

.
If `r`

is a matrix, it should have one row for each point in
`X`

. The algorithm
returns a matrix in which the entry on row `i`

,
column `j`

is the area of the
intersection between `W`

and the disc centred at `X[i]`

with radius `r[i,j]`

.

Areas are computed by analytic geometry.

##### Value

- Numeric matrix, with one row for each point of
`X`

.

##### See Also

##### Examples

```
data(letterR)
X <- runifpoint(3, letterR)
discpartarea(X, 0.2)
```

*Documentation reproduced from package spatstat, version 1.31-2, License: GPL (>= 2)*