[R-sig-eco] nearest neighbours - amended

[Anna Marburg]

Hello again Katia -

Of course, before you can use the functions in spdep, you will need to  
load it, like this:

library(spatstat)
library(spdep)
data(amacrine)

ama.split <- split(amacrine) # make one .ppp for each mark
summary(ama.split)

coords <- cbind(ama.split[["on"]]$x, ama.split[["on"]]$y)
class(coords)

rn <- 1:nrow(coords)	# if your points have meaningful ids put them here

# find 4 nearest neighbors:
k4 <- knn2nb(knearneigh(coords, k = 4), row.names = rn)

# calculate distances from each point to its neighbors
dsts <- nbdists(k4, coords)
summary(unlist(dsts))


# find all neighbors closer than some threshold
close.nb <- dnearneigh(coords, 0, 0.12330, row.names=rn)

# what do these different neighborhood objects look like?
summary(k4, coords)
summary(close.nb, coords)


# test the effect of different set logic
summary(intersect.nb(k4, close.nb), coords)

summary(union.nb(k4, close.nb), coords)


Sorry for the error,

Anna


Dr. Anna E.  Marburg
Ecosystem Processes Team
Landcare Research
P O Box 40
Lincoln 7640
NEW ZEALAND

phone + 64  3 321 9729
MarbugA at landcareresearch.co.nz


>
> Message: 1
> Date: Fri, 25 Sep 2009 11:31:08 -0400
> From: K?tia Emidio <kat.emidio at gmail.com>
> Subject: [R-sig-eco] nearest neighbours
> To: r-sig-ecology at r-project.org
> Message-ID:
> 	<cf3004ea0909250831n38dfd0bbl853e43d4b382da8d at mail.gmail.com>
> Content-Type: text/plain
>
> Hi, What function should I use to find out who are my 5 nearest  
> neigbours(N)
> or in a specified radius,  in a .ppp (object) where the marks are  
> factors?
> thanks
> Katia
>
> -- 
> K?tia Em?dio da Silva MSc
> Eng. Florestal
> Pesquisador
> Embrapa Amaz?nia Ocidental
>
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