R help - Nov 2009 - Re place only first NA in column

Dear All,

I am trying to fill in a blank vector ("a") with one value at a time,
with
the value of the number of rows in a randomized dataset with rowSums=0. 
Below is the code I've got so far, but what I want to be as the last line is
" a[1st NA,]=nz"
such that this will run until all of my NAs are replaced with an integer
value based on randomizations.

a<-matrix(nrow=1000,ncol=1)
while(sum(is.na(a)>0))
	{
	z<-matrix(rbinom(832, 1, prob = 0.048), nrow = 32)
	rs<-rowSums(z)
	nz<-length(rs[rs==0])
	a[,]=nz
		
}

Thank you for your help!
Mike
-- 
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Mike,

Is this what you're trying to do, it avoids the awkward use of a while loop,
taking advantage of the ability to vectorize R functions.

fun <- function() {
  z <- matrix(rbinom(832, 1, prob = 0.048), nrow = 32)
  sum(rowSums(z) == 0)
}

a <- as.matrix(replicate(1000, fun()))


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org]
> On Behalf Of bikemike42
> Sent: Tuesday, November 03, 2009 2:58 PM
> To: r-help at r-project.org
> Subject: [R] Re place only first NA in column
> 
> 
> Dear All,
> 
> I am trying to fill in a blank vector ("a") with one value at a
time, with
> the value of the number of rows in a randomized dataset with rowSums=0.
> Below is the code I've got so far, but what I want to be as the last
line
> is
> " a[1st NA,]=nz"
> such that this will run until all of my NAs are replaced with an integer
> value based on randomizations.
> 
> a<-matrix(nrow=1000,ncol=1)
> while(sum(is.na(a)>0))
> 	{
> 	z<-matrix(rbinom(832, 1, prob = 0.048), nrow = 32)
> 	rs<-rowSums(z)
> 	nz<-length(rs[rs==0])
> 	a[,]=nz
> 
> }
> 
> Thank you for your help!
> Mike
> --
> View this message in context: http://old.nabble.com/Replace-only-first-NA-
> in-column-tp26163589p26163589.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.

Hi,

On Nov 3, 2009, at 3:58 PM, bikemike42 wrote:
>
> Dear All,
>
> I am trying to fill in a blank vector ("a") with one value at a  
> time, with
> the value of the number of rows in a randomized dataset with  
> rowSums=0.
> Below is the code I've got so far, but what I want to be as the last  
> line is
> " a[1st NA,]=nz"
> such that this will run until all of my NAs are replaced with an  
> integer
> value based on randomizations.
>
> a<-matrix(nrow=1000,ncol=1)
> while(sum(is.na(a)>0))
> 	{
> 	z<-matrix(rbinom(832, 1, prob = 0.048), nrow = 32)
> 	rs<-rowSums(z)
> 	nz<-length(rs[rs==0])
> 	a[,]=nz
> 		
> }
>
> Thank you for your help!
It's not really clear to me what you want to actually replace each NA  
value with. But it sounds like your 'general' question is how to find  
the index of the first value of a vector that is NA.

Let's say your `a` vector has NA values you want to replace, one by one.

any.na <- any(is.na(a))
while (any.na) {
   first.na <- which(is.na(a))[1]
   a[first.na] <- your.NA.replacing.function()
   any.na <- any(is.na(a))
}

HTH,
-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
   |  Memorial Sloan-Kettering Cancer Center
   |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact