[R] dataframe operation

[Marc Schwartz]

On Wed, 2007-01-24 at 14:10 -0600, Marc Schwartz wrote:
> On Wed, 2007-01-24 at 20:27 +0100, Indermaur Lukas wrote:
> > hi
> > i have a dataframe "a" which looks like:
> >  
> > column1, column2, column3
> > 10,12, 0
> > NA, 0,1
> > 12,NA,50
> >  
> > i want to replace all values in column1 to column3 which do not contain "NA" with values of vector "b" (100,200,300).
> >  
> > any idea i can do it?
> >  
> > i appreciate any hint
> > regards
> > lukas
> >  
> 
> Here is one possibility:
> 
> > sapply(seq(along = colnames(DF)), 
>          function(x) ifelse(is.na(DF[[x]]), 100 * x, DF[[x]]))
>      [,1] [,2] [,3]
> [1,]   10   12    0
> [2,]  100    0    1
> [3,]   12  200   50
> 
> 
> Note that the returned object will be a matrix, so if you need a data
> frame, just coerce the result with as.data.frame().

OK....that's what I get for pulling the trigger too fast.

Just reverse the logic in the function:

> sapply(seq(along = colnames(DF)), 
         function(x) ifelse(!is.na(DF[[x]]), 100 * x, DF[[x]]))
     [,1] [,2] [,3]
[1,]  100  200  300
[2,]   NA  200  300
[3,]  100   NA  300


I misread the query initially.

HTH,

Marc