# centroid.owin

##### Centroid of a window

Computes the centroid (centre of mass) of a window

##### Usage

`centroid.owin(w, as.ppp = FALSE)`

##### Arguments

- w
- A window
- as.ppp
- Logical flag indicating whether to return the centroid
as a point pattern (
`ppp`

object)

##### Details

The centroid of the window `w`

is computed.
The centroid (``centre of mass'')
is the point whose $x$ and $y$ coordinates
are the mean values of the $x$ and $y$ coordinates
of all points in the window.

The argument `w`

should be a window (an object of class
`"owin"`

, see `owin.object`

for details)
or can be given in any format acceptable to `as.owin()`

.

The calculation uses an exact analytic formula for the case of polygonal windows.

Note that the centroid of a window is not necessarily inside
the window, unless the window is convex.
If `as.ppp=TRUE`

and
the centroid of `w`

lies outside `w`

,
then the window of the returned point pattern
will be a rectangle containing the
original window (using `as.rectangle`

.

##### Value

- Either a list with components
`x, y`

, or a point pattern (of class`ppp`

) consisting of a single point, giving the coordinates of the centroid of the window`w`

.

##### See Also

##### Examples

```
w <- owin(c(0,1),c(0,1))
centroid.owin(w)
# returns 0.5, 0.5
data(demopat)
w <- Window(demopat)
# an irregular window
cent <- centroid.owin(w, as.ppp = TRUE)
plot(cent)
# plot the window and its centroid
wapprox <- as.mask(w)
# pixel approximation of window
points(centroid.owin(wapprox))
# should be indistinguishable
<testonly>centroid.owin(w)
centroid.owin(wapprox)</testonly>
```

*Documentation reproduced from package spatstat, version 1.42-2, License: GPL (>= 2)*