[R] R-help

[MacQueen, Don]

A trip to the Spatial Task View on CRAN might be in order. The RandomFields package comes to mind.

-Don

--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
Lab cell 925-724-7509
 
 

On 11/9/17, 12:37 AM, "R-help on behalf of PIKAL Petr" <r-help-bounces at r-project.org on behalf of petr.pikal at precheza.cz> wrote:

    Hi
    
    it smells like a homework, this list has no homework policy.
    
    Anyway, maybe the sample approach could be used.
    
    Generate x,y coordinates - ?expand.grid
    sample n centers - ?sample
    select all points within defined area - ?point.in.polygon, package sp
    select desired number of points - ?sample
    
    Cheers
    Petr
    
    > -----Original Message-----
    > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of john lukore
    > Sent: Thursday, November 9, 2017 4:40 AM
    > To: r-help at r-project.org
    > Subject: [R] R-help
    >
    > Generate a clustered pattern in [0; 1]2 as follows:
    >
    > (a) Generate nc, say 20, independent cluster centres (which can be called
    > parents) that are distributed i.i.d. uniformly in the unit square;
    >
    >  (b) then n daughters are assigned i.i.d. uniformly to these parents and such
    > that each daughter is located i.i.d. uniformly in a disk of radius r =
    > 0:1 centred at her parent, under the periodic boundary conditions (i.e. the
    > square = a torus).
    >
    >
    > My attempt so far is:
    >
    >
    > set.seed(1) library(spatstat)
    >
    >  n_parent <- 2
    >
    >  n_daughter <- 4
    >
    > r = 0.1
    >
    > cnt <- n
    >
    > W <- disc(radius=3, centre=c(0,0)) i <- 1
    >
    >  while(i <= n_daughter){
    >
    > d_x <- runif(1)
    >
    > d_y <- runif(1)
    >
    > if (d_x ^2+d_y^2 <r) {
    >
    >  i = i+1}}
    >
    >
    > #need a condition here such that (d_x,d_y) lies in B(0,r)
    >
    >  #where B(0,r) is a ball of center origin and of radius r
    >
    > In above we should obtain one ball with n_daughters. Next step is to generate
    > parent centers and distribute the n_daughters in the ball into n_parents.
    >
    >       [[alternative HTML version deleted]]
    >
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