Note: I am almost certain that this has been asked and answered here
before, so my apologies for the redundant query.
I also know that there are several packages that will do this, but I wish
to do it using base R functions only (see below).
The query: Suppose I have a character vector of names like this:
somenames <- c("Heigh", "Ho", "Silver",
"Away")
(maybe dozens or hundreds: i.e. lots of names)
Now suppose want to put these in a model formula like this:
~ (Heigh + Ho + Silver + Away)^2
... But **without** pasting them into a character vector and using
parse(text = ...) , which, I grant, is sometimes the simplest way.
Instead, I want to do it using Base R's computing on the language
functions. I can do this with bquote() or substitute(), for example, like
this:
somenames <- c("Heigh", "Ho", "Silver",
"Away")
nms <- lapply(somenames, as.name)
form <- nms[[1]]
for(x in nms[-1])
form <<- bquote(.(form) + .(x), list(form = form, x = x))
## or form <<- substitute(form + x, list(form = form, x = x))
form <- bquote(~ (.(form))^2, list(form =form))
## yielding> form
~(Heigh + Ho + Silver + Away)^2
My question: Is there a simpler/slicker way to do this? This seems kinda
kludgy, and I have the feeling that I'm missing something obviously better
(in base R only; obviously better stuff is in various packages)
Best to all,
Bert
"An educated person is one who can entertain new ideas, entertain others,
and entertain herself."
[[alternative HTML version deleted]]
Richard M. Heiberger
2025-Mar-29 22:12 UTC
[R] [External] Creating model formulas programmatically
> somenames <- c("Heigh", "Ho", "Silver", "Away") > as.formula(paste("~(",paste(somenames, collapse="+"),")^2"))~(Heigh + Ho + Silver + Away)^2>> On Mar 29, 2025, at 14:30, Bert Gunter <bgunter.4567 at gmail.com> wrote: > > somenames <- c("Heigh", "Ho", "Silver", "Away")
Your approach seems reasonable to me, though I wouldn't do it that way.
The way I work this sort of thing out is to get R to do a simple
example, then see what it did, and duplicate that.
For example,
f <- ~ (Heigh + Ho + Silver + Away)^2
Then look at as.list(f), as.list(f[[2]]), as.list(f[[c(2,2)]]), etc.,
and reproduce that structure.
So I can reproduce that with
f <- ~(Heigh)^2
f[[c(2,2,2)]] <- call("+", f[[c(2,2,2)]],
as.name("Ho"))
f[[c(2,2,2)]] <- call("+", f[[c(2,2,2)]],
as.name("Silver"))
f[[c(2,2,2)]] <- call("+", f[[c(2,2,2)]],
as.name("Away"))
and there are obvious ways to convert that to work with names in a vector.
Duncan Murdoch
On 2025-03-29 5:30 p.m., Bert Gunter wrote:> Note: I am almost certain that this has been asked and answered here
> before, so my apologies for the redundant query.
>
> I also know that there are several packages that will do this, but I wish
> to do it using base R functions only (see below).
>
> The query: Suppose I have a character vector of names like this:
> somenames <- c("Heigh", "Ho", "Silver",
"Away")
> (maybe dozens or hundreds: i.e. lots of names)
>
> Now suppose want to put these in a model formula like this:
> ~ (Heigh + Ho + Silver + Away)^2
>
> ... But **without** pasting them into a character vector and using
> parse(text = ...) , which, I grant, is sometimes the simplest way.
> Instead, I want to do it using Base R's computing on the language
> functions. I can do this with bquote() or substitute(), for example, like
> this:
>
> somenames <- c("Heigh", "Ho", "Silver",
"Away")
> nms <- lapply(somenames, as.name)
> form <- nms[[1]]
> for(x in nms[-1])
> form <<- bquote(.(form) + .(x), list(form = form, x = x))
> ## or form <<- substitute(form + x, list(form = form, x = x))
> form <- bquote(~ (.(form))^2, list(form =form))
>
> ## yielding
>> form
> ~(Heigh + Ho + Silver + Away)^2
>
> My question: Is there a simpler/slicker way to do this? This seems kinda
> kludgy, and I have the feeling that I'm missing something obviously
better
> (in base R only; obviously better stuff is in various packages)
>
> Best to all,
> Bert
>
> "An educated person is one who can entertain new ideas, entertain
others,
> and entertain herself."
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
reformulate + update: somenames |> reformulate() |> update(~ (.)^2) On Sat, Mar 29, 2025 at 5:31?PM Bert Gunter <bgunter.4567 at gmail.com> wrote:> > Note: I am almost certain that this has been asked and answered here > before, so my apologies for the redundant query. > > I also know that there are several packages that will do this, but I wish > to do it using base R functions only (see below). > > The query: Suppose I have a character vector of names like this: > somenames <- c("Heigh", "Ho", "Silver", "Away") > (maybe dozens or hundreds: i.e. lots of names) > > Now suppose want to put these in a model formula like this: > ~ (Heigh + Ho + Silver + Away)^2 > > ... But **without** pasting them into a character vector and using > parse(text = ...) , which, I grant, is sometimes the simplest way. > Instead, I want to do it using Base R's computing on the language > functions. I can do this with bquote() or substitute(), for example, like > this: > > somenames <- c("Heigh", "Ho", "Silver", "Away") > nms <- lapply(somenames, as.name) > form <- nms[[1]] > for(x in nms[-1]) > form <<- bquote(.(form) + .(x), list(form = form, x = x)) > ## or form <<- substitute(form + x, list(form = form, x = x)) > form <- bquote(~ (.(form))^2, list(form =form)) > > ## yielding > > form > ~(Heigh + Ho + Silver + Away)^2 > > My question: Is there a simpler/slicker way to do this? This seems kinda > kludgy, and I have the feeling that I'm missing something obviously better > (in base R only; obviously better stuff is in various packages) > > Best to all, > Bert > > "An educated person is one who can entertain new ideas, entertain others, > and entertain herself." > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.-- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com
Another solution. reformulate + substitute + as.formula: substitute(~ (.)^2, list(. = reformulate(somenames)[[2]])) |> as.formula() On Sat, Mar 29, 2025 at 5:31?PM Bert Gunter <bgunter.4567 at gmail.com> wrote:> > Note: I am almost certain that this has been asked and answered here > before, so my apologies for the redundant query. > > I also know that there are several packages that will do this, but I wish > to do it using base R functions only (see below). > > The query: Suppose I have a character vector of names like this: > somenames <- c("Heigh", "Ho", "Silver", "Away") > (maybe dozens or hundreds: i.e. lots of names) > > Now suppose want to put these in a model formula like this: > ~ (Heigh + Ho + Silver + Away)^2 > > ... But **without** pasting them into a character vector and using > parse(text = ...) , which, I grant, is sometimes the simplest way. > Instead, I want to do it using Base R's computing on the language > functions. I can do this with bquote() or substitute(), for example, like > this: > > somenames <- c("Heigh", "Ho", "Silver", "Away") > nms <- lapply(somenames, as.name) > form <- nms[[1]] > for(x in nms[-1]) > form <<- bquote(.(form) + .(x), list(form = form, x = x)) > ## or form <<- substitute(form + x, list(form = form, x = x)) > form <- bquote(~ (.(form))^2, list(form =form)) > > ## yielding > > form > ~(Heigh + Ho + Silver + Away)^2 > > My question: Is there a simpler/slicker way to do this? This seems kinda > kludgy, and I have the feeling that I'm missing something obviously better > (in base R only; obviously better stuff is in various packages) > > Best to all, > Bert > > "An educated person is one who can entertain new ideas, entertain others, > and entertain herself." > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.-- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com