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)
## Not run:
# plot(cent)
# # plot the window and its centroid
# ## End(Not run)
wapprox < as.mask(w)
# pixel approximation of window
## Not run:
# points(centroid.owin(wapprox))
# # should be indistinguishable
# ## End(Not run)