Displaying 20 results from an estimated 700 matches similar to: "Spatstat: Mark correlation function"
2010 Apr 14
1
envelope in spatstat
Hi R users,
This query is regarding the use of the 'envelope' function in Spatstat.
My data can be represented as a point process with CONTINUOUS marks:
points <- ppp(x=x,y=y, marks=m, window= wind)
However the marks are alignments (lines), and so have to be treated
differently to normal scalar marks. Hence to create a mcf object with the
appropriate test function for alignment
2013 Feb 07
2
Spatstat - Kest, envelope problem
Hello,
I am writing cause I have a problem when try to create confidence envelopes
in spatstat.
I have a point data representing firms in my study area.
When I try to create confidence envelopes the error message turns up:
[> p <- envelope(point, fun=Kest, nsim=99)
Error in marks.ppp(Y, dfok = FALSE) :
Sorry, not implemented when the marks are a data frame]
Could you write me how can I
2009 Nov 20
1
Spatstat, markcorr, max. radius limited??
Hello,
could please somebody help me. I want to apply the mark correlation function but for radii up to 75 meters (in 75 individual 1m steps). Unfortunately, "There is a sensible default for the values of the argument r at which the mark correlation function kf (r) should be evaluated", so that I do not get results for r > 25m. Can I change something in the function to get the
2012 May 31
3
Quadrat counting with spatstat
I have photographs of plots that look like so:
http://r.789695.n4.nabble.com/file/n4631960/Untitled.jpg
I need to divide it up so each circle has an equal area surrounding it. So
into 20 equal segments, each of which contains a circle. Quadratcount is not
sufficient because if I divide it up into 36 equal quadrats, some quadrats
do not contain one of the circles.
I'm not even sure how to
2010 Nov 26
1
Plotting envelopes in spatstat
Hello,
Somehow I cannot control my envelope plots on Spatstat package. I would like
to plot an envelope with no legend and also I would like to label the plot
as such:
>plot(envelope(data, nsim=39, main="My K Plot", legend=FALSE,
xlab="Distance")
But somehow the "main", "legend" and "xlab" calls do not have any effect on
the plot. Can someone
2009 Feb 20
0
Random labeling hypothesis in spatstat
Hi,
I am trying to test the random labeling hypothesis with my data. I have a point pattern of bird nests and each nest has a mark that it is either predated or not-predated. I want to test the null hypothesis that the K distribution of predation events is equal to the K distribution of all events (nests). This is the code I am using:
Kdif <- function(X,...,i) {
Kidot <-
2012 Apr 16
2
Creating a point pattern with spatstat
I have presence/absence data in the following format:
1 2 3 4 5 6 7 8 9 10 11 12
1 1 1 1 1 1 1 1 1 1 1 1 0
2 1 1 1 1 0 1 1 1 1 1 1 0
3 1 1 1 1 1 1 1 1 1 1 0 1
4 1 1 1 1 1 0 1 1 1 1 0 1
5 1 1 1 1 1 1 1 0 0 1 1 1
6 1 1 1 0 0 1 0 0 1 1 1 1
7 1 1 1 1 0 1 1 0 0 0 1 1
8 1 1 1 1 1 1 1 0 0 0 1 0
9 1 1 1 1 0 0 1 0 0 0 1 1
10 1 1 1 1 1 1 1 0 0 0 0 1
11 1 1 1 1 1 1 1 1 1 0 0 1
12 1 1 1 1 1 0 0 0 1 1 1 1
2012 Jul 02
1
SPATSTAT: Minimum points for a Ripley K to be sensible?
Hello,
What are the minimum number of points in a point pattern before a
clustering analysis using a Ripley K function loses any meaning?
I haven't been able to find much comment in the literature about this
--- instead case examples typically use 100-200 points as a minimum.
Regards,
Sebastian Pucilowski
2010 Oct 07
3
quantile regression
Dear all,
I am a new user in r and I am facing some problems with the quantile regression specification. I have two matrix (mresultb and mresultx) with nrow=1000 and ncol=nsim, where I specify (let's say) nsim=10. Hence, the columns in my matrix represents each simulation of a determined variable. I need to regress each column of mresultb on mresultx. My codes are the following:
2010 Oct 13
1
(no subject)
Dear all,
I have just sent an email with my problem, but I think no one can see the red part, beacuse it is black. So, i am writing again the codes:
rm(list=ls()) #remove almost everything in the memory
set.seed(180185)
nsim <- 10
mresultx <- matrix(-99, nrow=1000, ncol=nsim)
mresultb <- matrix(-99, nrow=1000, ncol=nsim)
N <- 200
I <- 5
taus <- c(0.480:0.520)
h <-
2007 Oct 11
3
reason for error in small function?
Running the function below, tested using the cardiff dataset from
splancs generates the following error. What changes do I need to
make to get the function to work? Thanks. --Dale
> gen.rpoints(events, poly, 99)
> rpoints
Error: object "rpoints" not found
# test spatial data
library(splancs)
data(cardiff)
attach(cardiff)
str(cardiff)
events <- as.points(x,y)
###
2010 Oct 13
4
loop
Dear all,
I am trying to run a loop in my codes, but the software returns an error: "subscript out of bounds"
I dont understand exactly why this is happenning. My codes are the following:
rm(list=ls()) #remove almost everything in the memory
set.seed(180185)
nsim <- 10
mresultx <- matrix(-99, nrow=1000, ncol=nsim)
mresultb <- matrix(-99, nrow=1000, ncol=nsim)
N
2006 Jul 20
1
Loss of numerical precision from conversion to list ?
I?m working on an R-implementation of the simulation-based finite-sample null-distribution of (R)LR-Test in Mixed Models (i.e. testing for Var(RandomEffect)=0) derived by C. M. Crainiceanu and D. Ruppert.
I'm in the beginning stages of this project and while comparing quick and dirty grid-search-methods and more exact optim()/optimize()-based methods to find the maximum of a part of the
2011 Nov 07
1
How do I return to the row values of a matrix after computing distances
## Package Needed
library(fields)
## Assumptions
set.seed(123)
nsim<-5
p<-2
## Generate Random Matrix G
G <- matrix(runif(p*nsim),nsim,p)
## Set Empty Matraces dmax and dmin
dmax<- matrix(data=NA,nrow=nsim,ncol=p)
dmin<- matrix(data=NA,nrow=nsim,ncol=p)
## Loop to Fill dmax and dmin
for(i in 1:nsim) {
dmax[i]<- max(rdist(G[i,,drop=FALSE],G))
dmin[i]<-
2006 Feb 06
3
power and sample size for a GLM with poisson response variable
Hi all,
I would like to estimate power and necessary sample size for a GLM with
a response variable that has a poisson distribution. Do you have any
suggestions for how I can do this in R? Thank you for your help.
Sincerely,
Craig
--
Craig A. Faulhaber
Department of Forest, Range, and Wildlife Sciences
Utah State University
5230 Old Main Hill
Logan, UT 84322
(435)797-3892
2011 Feb 17
1
How to speed up a for() loop
Dear all,
Does anyone have any idea on how to speed up the for() loop below.
Currently it takes approximately 2 minutes and 30 seconds.
Because of the size of Nsim and N, simulating a multivariate normal
(instead of simulating Nsim times a vector of N normal distributions)
would require too much memory space.
Many thanks for your kind help,
Simona
N=3000
PD=runif(N,0,1)
cutoff.=qnorm(PD)
2007 Oct 03
2
Speeding up simulation of mean nearest neighbor distances
I've written the function below to simulate the mean 1st through nth
nearest neighbor distances for a random spatial pattern using the
functions nndist() and runifpoint() from spatsat. It works, but runs
relatively slowly - would appreciate suggestions on how to speed up
this function. Thanks. --Dale
library(spatstat)
sim.nth.mdist <- function(nth,nsim) {
D <- matrix(ncol=nth,
2009 Sep 02
1
problem in loop
Hi R-users,
I have a problem for updating the estimates of correlation coefficient in simulation loop.
I want to get the matrix of correlation coefficients (matrix, name: est) from geese by using loop(500 times) .
I used following code to update,
nsim<-500
est<-matrix(ncol=2, nrow=nsim)
for(i in 1:nsim){
fit <- geese(x ~ trt, id=subject, data=data_gee, family=binomial,
2006 Mar 08
1
power and sample size for a GLM with Poisson response variable
Craig, Thanks for your follow-up note on using the asypow package. My
problem was not only constructing the "constraints" vector but, for my
particular situation (Poisson regression, two groups, sample sizes of
(1081,3180), I get very different results using asypow package compared
to my other (home grown) approaches.
library(asypow)
pois.mean<-c(0.0065,0.0003)
info.pois <-
2007 Dec 04
1
Metropolis-Hastings within Gibbs coding error
Dear list,
After running for a while, it crashes and gives the following error message: can anybody suggest how to deal with this?
Error in if (ratio0[i] < log(runif(1))) { :
missing value where TRUE/FALSE needed
################### original program ########
p2 <- function (Nsim=1000){
x<- c(0.301,0,-0.301,-0.602,-0.903,-1.208, -1.309,-1.807,-2.108,-2.71) # logdose