[R] Adding NAs to data.frame

[Gabor Grothendieck]

That seems to be a suitable situation for a loop although you might
wish to write it like this:

for ( nm in names(df) )  df[ v[[nm]], nm ] <- NA

Note that R does not require semicolons at the end of each statement.

On Sat, May 8, 2010 at 11:12 AM,  <soeren.vogel at eawag.ch> wrote:
> Hello, after the creation of a data.frame I like to add NAs as follows:
>
> n <- 743;
> x <- runif(n, 1, 7);
> Y <- runif(n, 1, 7);
> Ag6 <- runif(n, 1, 7);
> df <- data.frame(x, Y, Ag6);
> # a list with positions:
> v <- apply(df, 2, function(x) sample(n, sample(1:ceiling(5*n/100), 1), repl=F));
> # a loop too much?
> for (i in 1:length(df)){
>  df[unlist(v[i]), i] <- NA;
> }
> summary(df);
>
> This works fine but it appears to me that there is a more elegant and simple way -- which one?
>
> Thanks
> Sören
>
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