Am 03.04.2012 17:43, schrieb Roosbeh Nowrouzian:
Thanks for the hint. I tried the syntax but I am getting error:
script:
# reading data
triplengthfile <- as.data.frame ( read.spss ( file =
"triplengthfile.sav" ) )
#Defining projection
coordinates ( triplengthfile ) <- cbind ( triplengthfile $ longa,
triplengthfile $ lata )
coords <- cbind ( triplengthfile $ longa, triplengthfile $ lata )
proj4string ( triplengthfile ) <- CRS ( "+proj=longlat +ellps=WGS84" )
#projecting to Albers conical
triplengthfile <- spTransform ( triplengthfile , CRS =
CRS ( "+proj=aea +lat_1=24 +lat_2=31.5 +lat_0=24 +lon_0=-84 +x_0=400000
+y_0=0 +ellps=GRS80 +units=m +no_defs" ) )
#updating coords
coords <- coordinates( triplengthfile )
IDs <- rownames ( triplengthfile@data )
#defining neighbors for Household members
HHneighbor.knn <- mapply ( function (n,coord) knearneigh ( x=coord, k=n,
longlat=FALSE, RANN=TRUE), HHNUM, lapply (1:nrow(coords),function(i)
coords[i,] ))
HHneighbor.knn <- mapply ( function (n,coord) knearneigh ( x=coord, k=n,
longlat=FALSE, RANN=TRUE), HHNUM, lapply(1:nrow(coords),function(i)
coords[i,,drop=FALSE] ))
which HHNUM is the number of HH members in matrix class (is defined for
each observation(individual))
But I am getting error:
Error:
Error in knearneigh(x = coord, k = n, longlat = FALSE, RANN = TRUE) :
Data not in matrix form
The error message is quite unambiguous, but its cause might be
confusing. "[" by default drops the dim-attribute, if a single row is
selected from a matrix. See ?"[" and the above example how to overcome
this (obviously it was, and still is untested).
Tom
Appreciate you could help me solve this error.
appreciate your help.
Roosbeh Nowrouzian
PhD student
Department of Civil Engineering
University of Florida
On Wed, Mar 28, 2012 at 10:35 PM, Tom Gottfried <[email protected]
<mailto:[email protected]>> wrote:
Hi,
Am 29.03.2012 01:08, schrieb Roosbeh Nowrouzian:
Hi list members:
Is there any way to define neighbors in R as any other observation
with distance to the corresponding point equal to 0.
I am trying to define neighbors base on the same location ( the same
Household members are linked to each other). I tried defining
weights base on fixed distance bounds:
neighbordistance.nb<- dnearneigh ( coords, d1=0, d2=0.00001,
row.names=IDs
)
But this function does not define other Household members
(distance=0) as
the neighbor.
When trying fixed number of neighbors:
neighbor3.knn<- knearneigh ( x=coords , k=3, longlat= FALSE,
RANN=TRUE )
This function defines other Household members(distance =0) as
neighbor but
the problem with this function is that each Household has different
Household number so different number of neighbors is required
for each
Household.
neighbor3.knn <-
mapply(function(n, coord) knearneigh(x=coord,
k=n, longlat=FALSE,RANN=TRUE),
ns, lapply(1:nrow(coords), function(i) coords[i,]))
Assuming you have a vector 'ns' with the number of household members
per household, this should give you a list with each element
defining the neighbours you desire. I hope I didn't misunderstand
your question.
HTH,
Tom
It would be kind of you letting me know if there is a way to define
neighbors base on zero distance with the corresponding point.
Appreciate it.
Roosbeh Nowrouzian
PhD student
Department of Civil Engineering
University of Florida
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