[R] inplace assignment

[David Hugh-Jones]

It's more a general point about having to write things out twice when
you do assignments. I could also have written:

data.frame[some.condition & another.condition, big.list.of.columns] <-
data.frame[some.condition & another.condition,  big.list.of.columns] * 2 + 55

or anything else. Equally, there could be any method of subsetting, or
any expression that can be an assignment target, on the left hand
side:

data.frame[[some.complex.expression.for.columnames]]
<-data.frame[[some.complex.expression.for.columnames]] * 333 + foo *
56

rownames(matrix)[45:53] <- paste(rownames(matrix)[45:53], "blah")


David

On 16/06/06, Adaikalavan Ramasamy <ramasamy at cancer.org.uk> wrote:
> I do not fully understand your question but how about :
>
>  inplace <- function( df, cond1, cond2, cols, suffix ){
>
>   w  <- which( cond1 & cond2 )
>   df <- df[ w, cols ]
>   paste(df, suffix)
>   return(df)
>  }
>
>
> BTW, did you mean "colnames(df) <- paste(colnames(df), suffix)" instead
> of "paste(df, suffix)" ?
>
> Regards, Adai
>
>
>
> On Fri, 2006-06-16 at 10:23 +0100, David Hugh-Jones wrote:
> > I get tired of writing, e.g.
> >
> >
> > data.frame[some.condition & another.condition, big.list.of.columns] <-
> > paste(data.frame[some.condition & another.condition,
> > big.list.of.columns], "foobar")
> >
> >
> > I would a function like:
> >
> > inplace(paste(data.frame[some.condition & another.condition,
> > big.list.of.columns], "foobar"))
> >
> > which would take the first argument of the inner function and assign
> > the function's result to it.
> >
> > Has anyone done something like this? Are there simple alternative
> > solutions that I'm missing?
> >
> > Cheers
> > David
> >
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>
>