>
> apply() operates on arrays and a data frame will be coerced to a matrix
> (which requires all elements to be of the same type). This is documented in
> ?apply.
>

Thanks, I was not aware of that. I implicitly assumed there would be a
specific apply.data.frame.



> This may not be elegant, but why not just use a loop:
>

The thing is that were are going to use this operation on a (very) large
scale in a production environment, on datasets for which nrow >> ncol. So I
would like the most efficient solution and if possibly, avoid looping over
the rows.

Thanks

Jeroen

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