[R] short question about data frame manipulation

[David Winsemius]

On Apr 30, 2010, at 9:08 AM, arnaud Gaboury wrote:

> Dear group,
>
> I am losing my mind with a simple question. Sorry if obvious, but I  
> maybe
> start to be confused after days and days of reading documentations.
>
> Df :
>
>
> df <-
> structure(list(a = 1:3, b = 4:6, c = structure(c(1L, 1L, 1L), class =
> "factor", .Label = "w")), .Names = c("a",
> "b", "c"), row.names = c(NA, -3L), class = "data.frame")
>
> I want to multiply first and second by -1.
>
>> x$a<-x$a*-1
>> x$b<-x$b*-1
>
> This returns what I want, but there must be an one line command to  
> do it,
> right?


 > df[ , -3] <- df[ , -3]*-1
 > df
    a  b c
1 -1 -4 w
2 -2 -5 w
3 -3 -6 w

>
-- 

David Winsemius, MD
West Hartford, CT