# polyarea

From geometry v0.3-6
by David Sterratt

##### Determines area of a polygon by triangle method.

Determines area of a polygon by triangle method. The variables
`x`

and `y`

define the vertex pairs, and must therefore
have the same shape. They can be either vectors or arrays. If
they are arrays then the columns of `x`

and `y`

are
treated separately and an area returned for each.

##### Usage

`polyarea(x, y, d = 1)`

##### Arguments

- x
X coordinates of verticies.

- y
Y coordinates of verticies.

- d
Dimension of array to work along.

##### Details

If the optional `dim`

argument is given, then `polyarea`

works along this dimension of the arrays `x`

and `y`

.

##### Value

Area(s) of polygon(s).

##### Examples

```
# NOT RUN {
x <- c(1, 1, 3, 3, 1)
y <- c(1, 3, 3, 1, 1)
polyarea(x, y)
polyarea(cbind(x, x), cbind(y, y)) ## c(4, 4)
polyarea(cbind(x, x), cbind(y,y), 1) ## c(4, 4)
polyarea(rbind(x, x), rbind(y,y), 2) ## c(4, 4)
# }
```

*Documentation reproduced from package geometry, version 0.3-6, License: GPL (>= 3) + file LICENSE*

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