[R] 2d rndom walk

[David Winsemius]

On Jun 29, 2011, at 11:44 AM, Komal wrote:

>
>
>
> walk.2d<-function(n)
> {
> rw <- matrix(0, ncol = 2, nrow = n)
>
> # generate the indices to set the deltas
> indx <- cbind(seq(n), sample(c(1, 2), n, TRUE))
>
> # now set the values
> rw[indx] <- sample(c(-1, 1), n, TRUE)
>
> # cumsum the columns
> rw[,1] <- cumsum(rw[, 1])
> rw[,2] <- cumsum(rw[, 2])
>
> return(rw[,1],rw[,2])
>
> }
> n<-1000
>
> plot(walk.2d(n), type="n",xlab="x",ylab="y",main="Random Walk  
> Simulation In
> Two Dimensions",xlim=range(rw[,1]),ylim=range(rw[,2]))
>
>        # use 'segments' to color each path
> segments(head(rw[, 1], -1), head(rw[, 2], -1), tail(rw[, 1], -1),  
> tail(rw[,
> 2], -1), col ="blue")
>
>
> This code is giving me error in the return()... what to write in  
> return()???

You are requested to post the _entire_ error message. It seems rather  
informative. You are giving two arguments to return() and it only  
accepts one. Probably better success with return(rw).

-- 
David Winsemius, MD
West Hartford, CT