# Random walk in 1 D
#
# From Seefeld and Linder, "Statistics Using R with Biological Examples."
# Modified by MVW 2018-01-31
#
# Inputs:          (default)
#    n     Number of steps to compute     (100)
#    p     Prob(x,x+1)                    (0.5)
#    seed  Random number seed             (NULL)
#
# Output:
#    Plot
#
Walk1d<-function(n=100, p=0.5, seed=NULL)
 {
   if( !is.null(seed) ) set.seed(seed);
   y<-vector(length=n); y[1]<-0;
   for(i in 2:n) y[i]<-y[(i-1)]+sample(c(-1,1),1,prob=c(1-p,p));
   lim <- max(c(y,abs(y)))+3;
   plot(1:n,y,type='l',ylim=c(-lim,lim));
 }