[R] Help with apply()

[David Winsemius]

On Feb 7, 2010, at 8:26 PM, Nathan S. Watson-Haigh wrote:

> I have a 2 column data.frame:
>
> > d[1:5,]
>  a b
> 1    80015     C
> 2    80016     B
> 3    80023     C
> 4    80062     B
> 5    80069     B
>
> I want to apply a function across each row:
>
> > for(i in 1:nrow(d)) {
> +    myFun(con, d[i,]$a, d[i,]$b)
> + }
>
> How do I do this using apply()? I'm unsure how to tell apply() to  
> pass data from columns a and b for a given row as arguments to the  
> function myFun().

apply(d, 1, function(x) myFun(x[1], x[2]) )

The reason you cannot use the "$" operator is that the row is passed  
to the function as a vector, rather than as a list.

-- 
David

>
> Thanks in advance for any pointers,
> Nathan
>
> -- 
> --------------------------------------------------------
> Dr. Nathan S. Watson-Haigh
> OCE Post Doctoral Fellow
> CSIRO Livestock Industries
> University Drive
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> Australia
>
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> Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
>
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