[R] converting NA/non-NA's to a binary variable

[Prof Brian Ripley]

mort[8] <- is.na(mort[4])

(If you really want 1/0, add  '+ 0' to this expression.)

Testing (in)equality with NA always gives NA.  This is discussed in all 
good books on S/R, e.g. in MASS (see the FAQ).

On Sat, 7 May 2005, Gillian Rutherford wrote:

> Dear R colleagues,
>
> I am trying to create a new column in a data frame, which converts values and 
> NA's from another column into binary format. Essentially I need the NA's to 
> become 1 and the rest to be 0. The code I wrote is returning the following 
> error message:
>
> Error in if (mort[i, 4] != NA) mort[i, 8] <- 0 else if (mort[i, 4] ==  :
>        missing value where TRUE/FALSE needed
>
> The code is as follows:
>
> for(i in 1:length(mort[,4]))
> 	{
> 		if(mort[i,4] != NA) mort[i,8] <- 0
> 		else if(mort[i,4] == NA) mort[i,8] <- 1
> 	}
>
> I'd appreciate any advice or recommendations as to a better way of achieving 
> this.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595