[R] Breaking up a vector

[AOLeary]

Hi all,

My problem is as follows: 

I want to run a loop which calculates two values and stores them in vectors
r and rv, respectively.
They're calculated from some vector x with length a multiple of 7.

x <- c(1:2058)

I need to difference the values but it would be incorrect to difference it
all in x, it has to be broken up first. I've tried the following:

r <- c(1:294)*0
rv <- c(1:294)*0

#RUN A LOOP WHERE YOU INPUT THE lx[(i-1)*7:i*7] INTO Z
for (i in 1:294){
#CREATE A NEW VECTOR OF LENGTH 7
z <- NULL
length(z)=7
dz <- NULL
dz2 <- NULL

#STORE THE VALUES IN z
z <- lx[1+(i-1)*7:(i)*7]

#THEN DIFFERENCE THOSE
#THIS IS r_t,i,m
dz=diff(z)

#SUM THIS UP AND STORE IT IN r, THIS IS r_t
r[i] <- sum(dz)

#SUM UP THE SQUARES AND STORE IT IN rv, THIS IS RV_t
dz2 <- dz^2
rv[i] <- sum(dz2)
#END THE LOOP
}


However, the window seems to expand for some reason, so z ends up being a
much longer vector than it should be and full of NAs.


Any help or advice is much appreciated.

Aodhán


--
View this message in context: http://r.789695.n4.nabble.com/Breaking-up-a-vector-tp4631329.html
Sent from the R help mailing list archive at Nabble.com.