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geometry (version 0.3-6)

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

## Description

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.

## Value

Area(s) of polygon(s).

## Details

If the optional `dim` argument is given, then `polyarea` works along this dimension of the arrays `x` and `y`.

## Examples

Run this code
``````# 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)
# }
``````

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