R help - Jun 2005 - without a loop

tmp <- c(-1,NA,NA,1,1,NA,NA,1)

without using a loop, how can I replace all NAs in the list above with
the previous none NA value in the list?

On Tue, 7 Jun 2005 11:02:13 -0400 Omar Lakkis wrote:
> tmp <- c(-1,NA,NA,1,1,NA,NA,1)
> 
> without using a loop, how can I replace all NAs in the list above with
> the previous none NA value in the list?
Package zoo contains a generic function na.locf (last observation
carried forward) which handles this:

R> tmp <- c(-1,NA,NA,1,1,NA,NA,1)
R> library(zoo)
R> na.locf(tmp)
[1] -1 -1 -1  1  1  1  1  1

Z
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How about the following:

tmp <- c(-1,NA,NA,1,1,NA,NA,1)

replaceNA <- function(x){
	iNA <- which(is.na(x))
	if(length(iNA) %in% c(0, length(x)))
		return(x)
	iNA1 <- iNA-1
	iNA1[iNA==0] <- length(x)
	x[iNA] <- x[iNA1]
	replaceNA(x)
}
 > replaceNA(tmp)
[1] -1 -1 -1  1  1  1  1  1
 > replaceNA(NA)
[1] NA

	  spencer graves

Omar Lakkis wrote:
> tmp <- c(-1,NA,NA,1,1,NA,NA,1)
> 
> without using a loop, how can I replace all NAs in the list above with
> the previous none NA value in the list?
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html

On 6/7/05, Omar Lakkis <uofiowa at gmail.com>
wrote:
> tmp <- c(-1,NA,NA,1,1,NA,NA,1)
> 
> without using a loop, how can I replace all NAs in the list above with
> the previous none NA value in the list?
This is known as last occurrence carried forward (LOCF) and
is implemented in both the 'zoo' and 'its' packages, e.g.

library(zoo)
na.locf(tmp)