[R] function doesn't change the variable in the right way

[fabian]

Hello

The function does exactly what you tell it to do; first you substitute 
all NA with the mean; then you subtract the mean;  for the NA this 
meand: mean-mean=0; and this is what you get.

the problem is not the function but the z-score of means.

lg fabian

On 07-03-2014 12:17, David Croll wrote:
> Dear R users and friends,
> 
> 
> I would like to ask you about the weird behaviour of a function I just
> wrote. This little function should take a vector, find NAs and
> substitute them for the mean of the vector, and return the normalized
> value of that vector.
> 
> I've tried both <- and <<- for changing the variables.
> 
> That's what I do:
> 
> # just a vector:
> b <- c(1,1,1,NA,3,2)
> 
> # my function:
> normalize <- function(x) {
> 
>     # copy x into new vector
>     xn <- x
> 
>     # index of NAs
>     nas <- which(is.na(xn) ==TRUE)
>     m <- mean(xn, na.rm=TRUE)
> 
>     # insert mean for NAs
>     xn[nas] <- m
> 
>     # normalize
>     return((xn - mean(xn))/sd(xn))
> 
> }
> 
> # run...
> normalize(b)
> 
> # here's what I get:
> # [1] -0.75 -0.75 -0.75  0.00  1.75  0.50
> 
> 
> The 4th value should be 1.6, but is 0.
> 
> 
> I believe the answer to my problem is pretty obvious, but I can't see 
> it...
> 
> 
> Best regards,
> 
> 
> David
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.