hello R-masters.
i have an R-issue here that i don't know if you'd wish to help me about it:
briefly i'd like to generate many (say hundred) realizations of a random walk,
execute a few operations on each of them (mean time of return), and graph each
realization on the same plot.
IN OTHER WORDS I'D LIKE TO IMPOSE A LOOPING CYCLE TO THE COMMAND NOT THE
ARGUMENT OF THE COMMAND.
for some of these questions i have already a partial answer: my main problem
here is automatizing the process for 100 times.
my random walk generating function is:
rwalk <- function(n,p, x0=0)
{
x <- rbinom(n,1,p)
x[which(x==0)] <- -1
y<-c(x0,x)
y <- cumsum(y)
}
THIS IS THE CODE THAT I'D LIKE TO REITERATE
a<- rwalk(n,p,x0=0) #whish to generate 100 of those
#and for each calculate the following
o<-which(a==0)
N<-length(o) # number of times the walk returns to 0
Nn<-(o[-1]-N) # number of steps to get to 0
V<-mean(Nn) # mean time of return to 0
par(mfrow=c(1,1))
plot(0:n, a, type= "l", main="...", xlab="tempo", ylab="stato",
ylim=c(...), lwd=3, col="red", lty=1)
par(new=T)
plot(0:n, b, type= "l", main="", xlab="", ylab="",
ylim=c(), lwd=3, col="green", lty=2)
#technically i've tryed to fuse all those parts in a function reiterating k=100
times with a for cycle, but with no succes, and i dare there must be something
really disturbing in the code below ....
function(k){
for (i in 1:k){
a[i]<-rwalk(1e+04,0.5,0)
o[i]<-which(a[i]==0)
N[i]<-length(o[i])
Nn[i]<-(o[i][-1]-N[i])
V[i]<-mean(Nn[i])
w<-c(V[1]:V[k])
M<-mean(w) #mean over all the realizations
par(mfrow=c(1,1))
plot(0:n, a[1], type= "l", main="...", xlab="tempo", ylab="stato",
ylim=c(...), lwd=3, col="red", lty=1)
par(new=T)
plot(0:n, a[i], type= "l", main="", xlab="", ylab="",
ylim=c(...), lwd=3, col=c(1:i), lty=2)
}
} #NOTE: I'VE ALSO TRIED TO REITERATE THE WALK WITH THE rep()
# t<-rep(rwalk(1e+04,0.5,0),100)
# then of course i have the problem of splicing this ridicolously #one
milion long vector in 100 bits of tenthousand, and still goig through all the
calculations and plotting i meant before....
i wonder what......
THANK YOU FOR YOUR PRECIUOS ATTENTION!!!
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