On Wed, Aug 1, 2012 at 4:19 PM, Ramiro Barrantes
<ram...@precisionbioassay.com> wrote:
> Hello,
>
> I come from using different programming languages (C++, Mathematica, Perl)
> but have been using R extensively for several months. I see the data frame
> as a key piece of the language and wanted to inquire people's experience
> regarding its use.
>
> Say you have a data frame D
>
> D <- data.frame(some columns)
>
> and you define a function that needs the information from this data frame and
> is supposed to return a calculation based on some columns of such data frame
> D.
>
> func <- function(d) {}
> #EFFECT: Does calculation X from some columns of d
>
> QUESTION: Would you consider better practice to return the same data.frame
> but expanded, or would you return a small data frame that consists of the
> newly computed columns?
I'd say return what you need, no more no less: and if you want to
reattach it to the input data, do that at the caller level, but don't
make it required: orthogonality and minimality and all that jazz....
As Bert points out, note that returning a data.frame is by no means
necessary -- they aren't "primitive" data structures like (atomic)
vectors and lists [we are in a Scheme dialect after all!], but they
are helpful and well supported. Use them liberally but no more than
necessary ;-)
Best,
Michael
>
> Some might say, either way, personal preference. But after using and seeing
> other's code for some time, I am thinking that returning the result that
> consists of ONLY the relevant columns is a better practice as it defines the
> function as only returning what it was intended to return, and leaves it up
> to the user of the function to do whatever they were intending to do with it
> (including naming of the new columns, adding them to a data frame, etc.).
> This might be a question for a computer programming theory group, but if
> anybody has any insight from their experience please share.
>
> Thanks in advance,
>
> Ramiro
>
> [[alternative HTML version deleted]]
>
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