(1) The manner in which you presented your data was a total mess.
If you ask for help, please have the courtesy to present your data in
such a manner that a potential "helper" can access it without needing to
do a great deal of editing and processing. Like so:
pts <- as.data.frame(matrix(c(415720,432795,415513,432834,415325,
432740,415356,432847,415374,432858,
415426,432774,415395,432811,415626,
432762),ncol=2,byrow=TRUE))
names(pts) <- c("x","y")
bdry <- as.data.frame(matrix(c(415491,432947,415269,432919,415211,
432776,415247,432657,415533,432657,
415781,432677,415795,432836,415746,
432937),ncol=2,byrow=TRUE))
names(bdry) <- c("x","y")
(2) Well, at least you presented a usable data set (even though the
presentation was lousy) which is better than what most posters do. And
you asked a "partially" clear question.
(3) I do not know what you mean by "Thiessen weights". I am guessing
that these are the areas of the Dirichlet tiles (Thiessen polygons),
intersected with the "boundary polygon" (i.e. observation window).
(4) If my guess is correct, the following should accomplish the desired
task:
require(spatstat) # You will (probably) need to install spatstat first.
W <- owin(poly=bdry)
X <- as.ppp(pts,W=W)
plot(X) # Just to make sure it looks right.
dX <- dirichlet(X)
plot(dX) # Just to make sure .....
sapply(tiles(dX),area.owin)
HTH
cheers,
Rolf Turner
On 22/04/15 02:50, Manoranjan Muthusamy wrote:
Hi R users,
I want to calculate Thiessen weights to compute areal rainfall from number
of point measurements. I am using R and thanks to some previous question in
the same topic, I got to know that I can usedeldir. But the problem is my
boundary polygon is not a rectangle; it's an irregular polygon (it's a
catchment boundary derived using ArcGIS). But in deldir the boundary can
only be a rectangle. Are there any other packages where I can calculate
Thiessen weights of an area covered by an irregular boundary?
Given below are my measurement points (meas_points) and coordinates of a
(simplified) boundary polygon(boundary)
meas_points
X Y[1,] 415720 432795[2,] 415513 432834[3,] 415325
432740[4,] 415356 432847[5,] 415374 432858[6,] 415426 432774[7,]
415395 432811[8,] 415626 432762
boundary
x y[1,] 415491 432947[2,] 415269 432919[3,] 415211
432776[4,] 415247 432657[5,] 415533 432657[6,] 415781 432677[7,]
415795 432836[8,] 415746 432937
Any help is really appreciated. Thanks.
--
Rolf Turner
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276
Home phone: +64-9-480-4619
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