[R] Replace NAs in one column with data from another column

[Dimitris Rizopoulos]

one way is the following:

m <- data.frame(x = rnorm(100), y = rnorm(100), z = rnorm(100))
m$z[sample(100, 20)] <- NA

m$z.new <- ifelse(is.na(m$z), m$x, m$z)


I hope it helps.

Best,
Dimitris


On 9/8/2010 8:17 PM, Jakob Hedegaard wrote:
> Hi list,
>
> I have a data frame (m) with 169221 rows and 10 columns and would like to make a new column containing the content of column 3 but replace the NAs in column 3 with the data in column 1 (from the same row as the NA in column 3). Column 1 has data in all rows.
>
> My first attempt was:
>
> for (i in 1:169221){
> if (is.na(m[i,3])==TRUE){
> m[i,11]<- as.character(m[i,1])}
> else{
> m[i,11]<- as.character(m[i,3])}
> }
>
> Works - but takes too long time.
> I would appreciate alternative solutions.
>
> Best regards, Jakob
>
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-- 
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

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