[R] Using with() to avoid $ ?
Jeff Newmiller
jdnewmil at dcn.davis.ca.us
Sun Oct 23 19:24:06 CEST 2016
No. And I don't know why you are conflating the treatment of variables in the formula with treatment of variables passed as other arguments. It is sort of like thinking the x symbols in foo$x[ x < 0 ] refer to the same data.
foo$y ~ foo$x1 + foo$x2 + foo$x3 is not preferable, and given the availability of a data argument such redundancy is unnecessary. NSE is already in use for the formula. It is not (necessarily) in use for the other arguments, so you just have to learn which arguments are being handled with NSE by any particular function and which are not... good docs would be the preferred avenue but recognizing the error message that arises when you fail to specify foo$ for the non-formula arguments gets me by if the docs are unclear.
However, it is dangerous to apply NSE tricks recursively, so piling "with" on top of the existing formula eval-with-data is only likely to confuse the evaluation context even more.
--
Sent from my phone. Please excuse my brevity.
On October 23, 2016 9:18:17 AM PDT, Bert Gunter <bgunter.4567 at gmail.com> wrote:
>As has been noted oftimes on this list
>f( y ~ x1 + x2 + x3 + ... , data = foo, ...)
>
>is much preferable to
>f( foo$y ~ foo$x1 + foo$x2 + foo$x3 + ..., ...)
>
>(with no data argument), using nse = non-standard evaluation to set the
>environment for formula evaluation. However, as queries here recently
>demonstrate, the formula variables (y, x1, x2, x3, ...) or other
>variables
>in foo are also sometimes needed as further arguments of f, and these
>have
>to be explicitly and tediously given as foo$whatever or equivalent
>indexing.
>
>So my question is, can/should with() be used instead in the form
>with(foo, f( y ~ x1 + x2 + x3 + ... , data = foo, ...)) with no
>explicit
>$ or indexing in ... variables?
>
>or even
>with(foo, f( y ~ x1 + x2 + x3 + ... , ...))
>
>with no data argument for nse or indexing, though this seems to me
>questionable in that it may affect the formula's environment
>differently.(??)
>
>Please correct any misstatements of fact in the above as well as
>clarifying
>anything else I seem confused about.
>
>Many thanks.
>
>Bert
>
> [[alternative HTML version deleted]]
>
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