Thank you all for your reply. I should clarify, that I am looking to understand
why the keyword function can take a logical argument (eg: x<4) and use that
later inside the function's definition for logical evaluations.
Consider this example, which is a simplification of
getAnywhere(subset.data.frame):
x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" = c(6, 7,
8, 9, 10))
test <- function(x, logic){
e <- substitute(logic)
r <- eval(e, x, parent.frame())
r[r]
}
Shelby
?On 9/6/19, 1:02 PM, "R-help on behalf of Richard M. Heiberger"
<r-help-bounces at r-project.org on behalf of rmh at temple.edu> wrote:
You might also want to look at the codetools package, for example the
showTree function " Prints a Lisp-style representation of R
expression."
> library(codetools)
> showTree(quote(x %*% x))
(%*% x x)
> showTree(quote(a+b))
(+ a b)
> showTree(quote(y ~ a+b))
(~ y (+ a b))
On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at gmail.com>
wrote:
>
> The following may be of use (it gives the parse tree of the text):
>
> > z <- as.list(parse(text = "function(x)x %*% x"))
> > z[[1]]
> function(x) x %*% x
> > z[[c(1,1)]]
> `function`
> > z[[c(1,2)]]
> $x
> > z[[c(1,3)]]
> x %*% x
> > z[[c(1,3,1)]]
> `%*%`
> > z[[c(1,3,2)]]
> x
> > z[[c(1,3,3)]]
> x
>
>
> Bert Gunter
>
>
>
> On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at
gmail.com> wrote:
>
> > If you are looking for an R code parser, I think the `parse` and
`eval`
> > function might be a good start point. See the example below.
> >
> > > parse(text="function(x)message(x)")
> > expression(function(x)message(x))
> > > eval(parse(text="function(x)message(x)"))
> > function(x)message(x)
> >
> > Best,
> > Jiefei
> >
> > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby <GoldenS at
njhealth.org>
> > wrote:
> >
> >> Hello Bert,
> >>
> >> Thank you for the reply and your clarifications. Yes, it might
be helpful
> >> to look into R?s formal grammar to see how ?function? parses
input to
> >> delegate correct syntax. Is that accessible online?
> >>
> >> Thank you,
> >> Shelby
> >>
> >>
> >> From: Bert Gunter <bgunter.4567 at gmail.com>
> >> Date: Friday, September 6, 2019 at 10:44 AM
> >> To: "Golden, Shelby" <GoldenS at NJHealth.org>
> >> Cc: "r-help at R-project.org" <r-help at
r-project.org>, "Gillenwater, Lucas" <
> >> GILLENWATERL at NJHEALTH.ORG>
> >> Subject: Re: [R] [R-devel] Source Code for function
> >>
> >> 1. This is a plain text list; all html is stripped. So there
is no red
> >> highlighting.
> >>
> >> 2. There is no "source code" for
"function" -- it is a reserved keyword.
> >> Or are you looking for R's formal grammar -- e.g. how it
parses input to
> >> determine correct syntax?
> >>
> >>
> >>
> >> Bert Gunter
> >>
> >> "The trouble with having an open mind is that people keep
coming along
> >> and sticking things into it."
> >> -- Opus (aka Berkeley Breathed in his "Bloom County"
comic strip )
> >>
> >>
> >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby <GoldenS at
njhealth.org
> >> <mailto:GoldenS at njhealth.org>> wrote:
> >> Hi all,
> >>
> >> I have been attempting to access the source code for the
keyword
> >> ?function? to better understand how it assigns and stores
logical inputs,
> >> like in the subset() [base] function. Does anyone know how I
can access the
> >> source code for this?
> >>
> >> For example, if I have
> >> norm <- function(x){
> >> sqrt(x%*%x))
> >> }
> >> I am looking for the source code for the ?function? portion,
highlighted
> >> in red.
> >>
> >> Thank you for your time and assistance,
> >> Shelby Golden
> >> Lab Researcher Technician
> >> Dr. Russell Bowler?s Lab
> >> Department of Medicine
> >> National Jewish Health in Denver, CO
> >> Phone: (303) 270-2598
> >>
> >> NOTICE: This email message is for the sole use of the intended
> >> recipient(s) and may contain confidential and privileged
information. Any
> >> unauthorized review, use, disclosure or distribution is
prohibited. If you
> >> are not the intended recipient, please contact the sender by
reply email
> >> and destroy all copies of the original message.
> >> [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
> >> R-help at r-project.org<mailto:R-help at r-project.org>
mailing list -- To
> >> UNSUBSCRIBE and more, see
> >> https://stat.ethz.ch/mailman/listinfo/r-help<
> >>
http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZmMWRiYmMxZjFmNmI5ZDBkMz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJjljNzlmMDA4YWRmZTZjMz0xMjMzJiZ1cmw9aHR0cHMlM0ElMkYlMkZzdGF0JTJFZXRoeiUyRWNoJTJGbWFpbG1hbiUyRmxpc3RpbmZvJTJGci1oZWxw
> >> >
> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html<
> >>
http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZlMTkwYmMwMzFlNjk4ZTAzNz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJmFkYTkxMWRkMWRhZTFkNz0xMjMzJiZ1cmw9aHR0cCUzQSUyRiUyRnd3dyUyRVItcHJvamVjdCUyRW9yZyUyRnBvc3RpbmctZ3VpZGUlMkVodG1s
> >> >
> >> and provide commented, minimal, self-contained, reproducible
code.
> >>
> >> [[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
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible
code.
> >>
> >
>
> [[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
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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 http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
NOTICE: This email message is for the sole use of the intended recipient(s) and
may contain confidential and privileged information. Any unauthorized review,
use, disclosure or distribution is prohibited. If you are not the intended
recipient, please contact the sender by reply email and destroy all copies of
the original message.
On 9/6/19 1:07 PM, Golden, Shelby wrote:> Thank you all for your reply. I should clarify, that I am looking to understand why the keyword function can take a logical argument (eg: x<4) and use that later inside the function's definition for logical evaluations. > > Consider this example, which is a simplification of getAnywhere(subset.data.frame): > x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" = c(6, 7, 8, 9, 10)) > test <- function(x, logic){ > e <- substitute(logic) > r <- eval(e, x, parent.frame()) > r[r] > }x<4 is not really a logical argument in that context. It is rather an expression and will remain an expression until it needs to be evaluated. See this even simpler example: ?test <- function(x, logic, ... ){ ???? e <- deparse( substitute(logic)) ???? #r <- eval(e, x, parent.frame()) ???? e ?} ?test(4, x<4) #[1] "x < 4" ?test(4, is.logical(x < 4) ) [1] "is.logical(x < 4)" Some of this you have already been told, but appears necessary to repeat. Expressions given to `function` are not necessarily evaluated. They will be evaluated if assigned names. test(4, zed = is.logical(x < 4) ) #[1] "" The function()-function will parse the contents of the parentheses for number of arguments and for parse()-ability. It will evaluate named arguments created with "=". In the context of parsing the formals of a function the "=" operator is different than the "<-" function. The substitute function will not evaluate (since in the language of R operations it is "special"), but rather checks that the expression can be parsed by R's rules, i.e. is a valid parse tree. `deparse` returns the original character representation. -- David> > Shelby > > > ?On 9/6/19, 1:02 PM, "R-help on behalf of Richard M. Heiberger" <r-help-bounces at r-project.org on behalf of rmh at temple.edu> wrote: > > You might also want to look at the codetools package, for example the > showTree function " Prints a Lisp-style representation of R > expression." > > > library(codetools) > > > showTree(quote(x %*% x)) > (%*% x x) > > showTree(quote(a+b)) > (+ a b) > > showTree(quote(y ~ a+b)) > (~ y (+ a b)) > > On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at gmail.com> wrote: > > > > The following may be of use (it gives the parse tree of the text): > > > > > z <- as.list(parse(text = "function(x)x %*% x")) > > > z[[1]] > > function(x) x %*% x > > > z[[c(1,1)]] > > `function` > > > z[[c(1,2)]] > > $x > > > z[[c(1,3)]] > > x %*% x > > > z[[c(1,3,1)]] > > `%*%` > > > z[[c(1,3,2)]] > > x > > > z[[c(1,3,3)]] > > x > > > > > > Bert Gunter > > > > > > > > On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at gmail.com> wrote: > > > > > If you are looking for an R code parser, I think the `parse` and `eval` > > > function might be a good start point. See the example below. > > > > > > > parse(text="function(x)message(x)") > > > expression(function(x)message(x)) > > > > eval(parse(text="function(x)message(x)")) > > > function(x)message(x) > > > > > > Best, > > > Jiefei > > > > > > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby <GoldenS at njhealth.org> > > > wrote: > > > > > >> Hello Bert, > > >> > > >> Thank you for the reply and your clarifications. Yes, it might be helpful > > >> to look into R?s formal grammar to see how ?function? parses input to > > >> delegate correct syntax. Is that accessible online? > > >> > > >> Thank you, > > >> Shelby > > >> > > >> > > >> From: Bert Gunter <bgunter.4567 at gmail.com> > > >> Date: Friday, September 6, 2019 at 10:44 AM > > >> To: "Golden, Shelby" <GoldenS at NJHealth.org> > > >> Cc: "r-help at R-project.org" <r-help at r-project.org>, "Gillenwater, Lucas" < > > >> GILLENWATERL at NJHEALTH.ORG> > > >> Subject: Re: [R] [R-devel] Source Code for function > > >> > > >> 1. This is a plain text list; all html is stripped. So there is no red > > >> highlighting. > > >> > > >> 2. There is no "source code" for "function" -- it is a reserved keyword. > > >> Or are you looking for R's formal grammar -- e.g. how it parses input to > > >> determine correct syntax? > > >> > > >> > > >> > > >> Bert Gunter > > >> > > >> "The trouble with having an open mind is that people keep coming along > > >> and sticking things into it." > > >> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > >> > > >> > > >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby <GoldenS at njhealth.org > > >> <mailto:GoldenS at njhealth.org>> wrote: > > >> Hi all, > > >> > > >> I have been attempting to access the source code for the keyword > > >> ?function? to better understand how it assigns and stores logical inputs, > > >> like in the subset() [base] function. Does anyone know how I can access the > > >> source code for this? > > >> > > >> For example, if I have > > >> norm <- function(x){ > > >> sqrt(x%*%x)) > > >> } > > >> I am looking for the source code for the ?function? portion, highlighted > > >> in red. > > >> > > >> Thank you for your time and assistance, > > >> Shelby Golden > > >> Lab Researcher Technician > > >> Dr. Russell Bowler?s Lab > > >> Department of Medicine > > >> National Jewish Health in Denver, CO > > >> Phone: (303) 270-2598 > > >> > > >> NOTICE: This email message is for the sole use of the intended > > >> recipient(s) and may contain confidential and privileged information. Any > > >> unauthorized review, use, disclosure or distribution is prohibited. If you > > >> are not the intended recipient, please contact the sender by reply email > > >> and destroy all copies of the original message. > > >> [[alternative HTML version deleted]] > > >> > > >> ______________________________________________ > > >> R-help at r-project.org<mailto:R-help at r-project.org> mailing list -- To > > >> UNSUBSCRIBE and more, see > > >> https://stat.ethz.ch/mailman/listinfo/r-help< > > >> http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZmMWRiYmMxZjFmNmI5ZDBkMz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJjljNzlmMDA4YWRmZTZjMz0xMjMzJiZ1cmw9aHR0cHMlM0ElMkYlMkZzdGF0JTJFZXRoeiUyRWNoJTJGbWFpbG1hbiUyRmxpc3RpbmZvJTJGci1oZWxw > > >> > > > >> PLEASE do read the posting guide > > >> http://www.R-project.org/posting-guide.html< > > >> http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZlMTkwYmMwMzFlNjk4ZTAzNz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJmFkYTkxMWRkMWRhZTFkNz0xMjMzJiZ1cmw9aHR0cCUzQSUyRiUyRnd3dyUyRVItcHJvamVjdCUyRW9yZyUyRnBvc3RpbmctZ3VpZGUlMkVodG1s > > >> > > > >> and provide commented, minimal, self-contained, reproducible code. > > >> > > >> [[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 > > >> http://www.R-project.org/posting-guide.html > > >> and provide commented, minimal, self-contained, reproducible code. > > >> > > > > > > > [[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 http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > 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 http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > > > NOTICE: This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. > ______________________________________________ > 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 http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
Afternoon, David,
Thank you for your suggestions and insight. I have previously utilized parse,
but in my exploration to improve my coding technique I came across this comment
in stackoverflow.com
(https://stackoverflow.com/questions/1743698/evaluate-expression-given-as-a-string
- comment left Martin Maechler). In it, he suggests that usage parse is not a
good method, saying that it is "rarely an efficient or safe means to
construct expressions (or calls)".
Perhaps you, or others in this community, disagree with what Martin has to say
about parse in this application?
Shelby
?On 9/6/19, 3:10 PM, "David Winsemius" <dwinsemius at
comcast.net> wrote:
On 9/6/19 1:07 PM, Golden, Shelby wrote:
> Thank you all for your reply. I should clarify, that I am looking to
understand why the keyword function can take a logical argument (eg: x<4) and
use that later inside the function's definition for logical evaluations.
>
> Consider this example, which is a simplification of
getAnywhere(subset.data.frame):
> x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" =
c(6, 7, 8, 9, 10))
> test <- function(x, logic){
> e <- substitute(logic)
> r <- eval(e, x, parent.frame())
> r[r]
> }
x<4 is not really a logical argument in that context. It is rather an
expression and will remain an expression until it needs to be evaluated.
See this even simpler example:
test <- function(x, logic, ... ){
e <- deparse( substitute(logic))
#r <- eval(e, x, parent.frame())
e
}
test(4, x<4)
#[1] "x < 4"
test(4, is.logical(x < 4) )
[1] "is.logical(x < 4)"
Some of this you have already been told, but appears necessary to
repeat. Expressions given to `function` are not necessarily evaluated.
They will be evaluated if assigned names.
test(4, zed = is.logical(x < 4) )
#[1] ""
The function()-function will parse the contents of the parentheses for
number of arguments and for parse()-ability. It will evaluate named
arguments created with "=". In the context of parsing the formals
of a
function the "=" operator is different than the "<-"
function.
The substitute function will not evaluate (since in the language of R
operations it is "special"), but rather checks that the expression
can
be parsed by R's rules, i.e. is a valid parse tree. `deparse` returns
the original character representation.
--
David
>
> Shelby
>
>
> On 9/6/19, 1:02 PM, "R-help on behalf of Richard M.
Heiberger" <r-help-bounces at r-project.org on behalf of rmh at
temple.edu> wrote:
>
> You might also want to look at the codetools package, for example
the
> showTree function " Prints a Lisp-style representation of R
> expression."
>
> > library(codetools)
>
> > showTree(quote(x %*% x))
> (%*% x x)
> > showTree(quote(a+b))
> (+ a b)
> > showTree(quote(y ~ a+b))
> (~ y (+ a b))
>
> On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at
gmail.com> wrote:
> >
> > The following may be of use (it gives the parse tree of the
text):
> >
> > > z <- as.list(parse(text = "function(x)x %*%
x"))
> > > z[[1]]
> > function(x) x %*% x
> > > z[[c(1,1)]]
> > `function`
> > > z[[c(1,2)]]
> > $x
> > > z[[c(1,3)]]
> > x %*% x
> > > z[[c(1,3,1)]]
> > `%*%`
> > > z[[c(1,3,2)]]
> > x
> > > z[[c(1,3,3)]]
> > x
> >
> >
> > Bert Gunter
> >
> >
> >
> > On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at
gmail.com> wrote:
> >
> > > If you are looking for an R code parser, I think the
`parse` and `eval`
> > > function might be a good start point. See the example
below.
> > >
> > > > parse(text="function(x)message(x)")
> > > expression(function(x)message(x))
> > > > eval(parse(text="function(x)message(x)"))
> > > function(x)message(x)
> > >
> > > Best,
> > > Jiefei
> > >
> > > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby
<GoldenS at njhealth.org>
> > > wrote:
> > >
> > >> Hello Bert,
> > >>
> > >> Thank you for the reply and your clarifications.
Yes, it might be helpful
> > >> to look into R?s formal grammar to see how
?function? parses input to
> > >> delegate correct syntax. Is that accessible online?
> > >>
> > >> Thank you,
> > >> Shelby
> > >>
> > >>
> > >> From: Bert Gunter <bgunter.4567 at gmail.com>
> > >> Date: Friday, September 6, 2019 at 10:44 AM
> > >> To: "Golden, Shelby" <GoldenS at
NJHealth.org>
> > >> Cc: "r-help at R-project.org" <r-help
at r-project.org>, "Gillenwater, Lucas" <
> > >> GILLENWATERL at NJHEALTH.ORG>
> > >> Subject: Re: [R] [R-devel] Source Code for function
> > >>
> > >> 1. This is a plain text list; all html is stripped.
So there is no red
> > >> highlighting.
> > >>
> > >> 2. There is no "source code" for
"function" -- it is a reserved keyword.
> > >> Or are you looking for R's formal grammar --
e.g. how it parses input to
> > >> determine correct syntax?
> > >>
> > >>
> > >>
> > >> Bert Gunter
> > >>
> > >> "The trouble with having an open mind is that
people keep coming along
> > >> and sticking things into it."
> > >> -- Opus (aka Berkeley Breathed in his "Bloom
County" comic strip )
> > >>
> > >>
> > >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby
<GoldenS at njhealth.org
> > >> <mailto:GoldenS at njhealth.org>> wrote:
> > >> Hi all,
> > >>
> > >> I have been attempting to access the source code for
the keyword
> > >> ?function? to better understand how it assigns and
stores logical inputs,
> > >> like in the subset() [base] function. Does anyone
know how I can access the
> > >> source code for this?
> > >>
> > >> For example, if I have
> > >> norm <- function(x){
> > >> sqrt(x%*%x))
> > >> }
> > >> I am looking for the source code for the ?function?
portion, highlighted
> > >> in red.
> > >>
> > >> Thank you for your time and assistance,
> > >> Shelby Golden
> > >> Lab Researcher Technician
> > >> Dr. Russell Bowler?s Lab
> > >> Department of Medicine
> > >> National Jewish Health in Denver, CO
> > >> Phone: (303) 270-2598
> > >>
> > >> NOTICE: This email message is for the sole use of
the intended
> > >> recipient(s) and may contain confidential and
privileged information. Any
> > >> unauthorized review, use, disclosure or distribution
is prohibited. If you
> > >> are not the intended recipient, please contact the
sender by reply email
> > >> and destroy all copies of the original message.
> > >> [[alternative HTML version deleted]]
> > >>
> > >> ______________________________________________
> > >> R-help at r-project.org<mailto:R-help at
r-project.org> mailing list -- To
> > >> UNSUBSCRIBE and more, see
> > >> https://stat.ethz.ch/mailman/listinfo/r-help<
> > >>
http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZmMWRiYmMxZjFmNmI5ZDBkMz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJjljNzlmMDA4YWRmZTZjMz0xMjMzJiZ1cmw9aHR0cHMlM0ElMkYlMkZzdGF0JTJFZXRoeiUyRWNoJTJGbWFpbG1hbiUyRmxpc3RpbmZvJTJGci1oZWxw
> > >> >
> > >> PLEASE do read the posting guide
> > >> http://www.R-project.org/posting-guide.html<
> > >>
http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZlMTkwYmMwMzFlNjk4ZTAzNz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJmFkYTkxMWRkMWRhZTFkNz0xMjMzJiZ1cmw9aHR0cCUzQSUyRiUyRnd3dyUyRVItcHJvamVjdCUyRW9yZyUyRnBvc3RpbmctZ3VpZGUlMkVodG1s
> > >> >
> > >> and provide commented, minimal, self-contained,
reproducible code.
> > >>
> > >> [[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
> > >> http://www.R-project.org/posting-guide.html
> > >> and provide commented, minimal, self-contained,
reproducible code.
> > >>
> > >
> >
> > [[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
http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible
code.
>
> ______________________________________________
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Um... Let's get the concepts straight: The "function" function doesn't evaluate anything. It just takes the list of formal arguments (including default expressions), the function body, and the current evaluation environment, and stiches them together into a function object, known as a "closure". The action happens when a function is _called_. Then the actual arguments are combined with the formals, and the body expression is evaluated. You will find the source code for this in src/main/eval.c. It is a pretty complex beast, but the essential point for the present discussion is that actual arguments in function calls are passed in the form of so-called promises. These contain the expression passed, so that substitute() can extract it. It also enables lazy evaluation: putting off argument evaluation until the value is actually needed (possibly never). -pd> On 6 Sep 2019, at 23:10 , David Winsemius <dwinsemius at comcast.net> wrote: > > > On 9/6/19 1:07 PM, Golden, Shelby wrote: >> Thank you all for your reply. I should clarify, that I am looking to understand why the keyword function can take a logical argument (eg: x<4) and use that later inside the function's definition for logical evaluations. >> >> Consider this example, which is a simplification of getAnywhere(subset.data.frame): >> x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" = c(6, 7, 8, 9, 10)) >> test <- function(x, logic){ >> e <- substitute(logic) >> r <- eval(e, x, parent.frame()) >> r[r] >> } > > x<4 is not really a logical argument in that context. It is rather an expression and will remain an expression until it needs to be evaluated. See this even simpler example: > > > test <- function(x, logic, ... ){ > e <- deparse( substitute(logic)) > #r <- eval(e, x, parent.frame()) > e > } > test(4, x<4) > #[1] "x < 4" > > > test(4, is.logical(x < 4) ) > [1] "is.logical(x < 4)" > > > Some of this you have already been told, but appears necessary to repeat. Expressions given to `function` are not necessarily evaluated. They will be evaluated if assigned names. > > > test(4, zed = is.logical(x < 4) ) > #[1] "" > > The function()-function will parse the contents of the parentheses for number of arguments and for parse()-ability. It will evaluate named arguments created with "=". In the context of parsing the formals of a function the "=" operator is different than the "<-" function. > > The substitute function will not evaluate (since in the language of R operations it is "special"), but rather checks that the expression can be parsed by R's rules, i.e. is a valid parse tree. `deparse` returns the original character representation. > > -- > > David > > >> >> Shelby >> >> ?On 9/6/19, 1:02 PM, "R-help on behalf of Richard M. Heiberger" <r-help-bounces at r-project.org on behalf of rmh at temple.edu> wrote: >> >> You might also want to look at the codetools package, for example the >> showTree function " Prints a Lisp-style representation of R >> expression." >> > library(codetools) >> > showTree(quote(x %*% x)) >> (%*% x x) >> > showTree(quote(a+b)) >> (+ a b) >> > showTree(quote(y ~ a+b)) >> (~ y (+ a b)) >> On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at gmail.com> wrote: >> > >> > The following may be of use (it gives the parse tree of the text): >> > >> > > z <- as.list(parse(text = "function(x)x %*% x")) >> > > z[[1]] >> > function(x) x %*% x >> > > z[[c(1,1)]] >> > `function` >> > > z[[c(1,2)]] >> > $x >> > > z[[c(1,3)]] >> > x %*% x >> > > z[[c(1,3,1)]] >> > `%*%` >> > > z[[c(1,3,2)]] >> > x >> > > z[[c(1,3,3)]] >> > x >> > >> > >> > Bert Gunter >> > >> > >> > >> > On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at gmail.com> wrote: >> > >> > > If you are looking for an R code parser, I think the `parse` and `eval` >> > > function might be a good start point. See the example below. >> > > >> > > > parse(text="function(x)message(x)") >> > > expression(function(x)message(x)) >> > > > eval(parse(text="function(x)message(x)")) >> > > function(x)message(x) >> > > >> > > Best, >> > > Jiefei >> > > >> > > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby <GoldenS at njhealth.org> >> > > wrote: >> > > >> > >> Hello Bert, >> > >> >> > >> Thank you for the reply and your clarifications. Yes, it might be helpful >> > >> to look into R?s formal grammar to see how ?function? parses input to >> > >> delegate correct syntax. Is that accessible online? >> > >> >> > >> Thank you, >> > >> Shelby >> > >> >> > >> >> > >> From: Bert Gunter <bgunter.4567 at gmail.com> >> > >> Date: Friday, September 6, 2019 at 10:44 AM >> > >> To: "Golden, Shelby" <GoldenS at NJHealth.org> >> > >> Cc: "r-help at R-project.org" <r-help at r-project.org>, "Gillenwater, Lucas" < >> > >> GILLENWATERL at NJHEALTH.ORG> >> > >> Subject: Re: [R] [R-devel] Source Code for function >> > >> >> > >> 1. This is a plain text list; all html is stripped. So there is no red >> > >> highlighting. >> > >> >> > >> 2. There is no "source code" for "function" -- it is a reserved keyword. >> > >> Or are you looking for R's formal grammar -- e.g. how it parses input to >> > >> determine correct syntax? >> > >> >> > >> >> > >> >> > >> Bert Gunter >> > >> >> > >> "The trouble with having an open mind is that people keep coming along >> > >> and sticking things into it." >> > >> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) >> > >> >> > >> >> > >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby <GoldenS at njhealth.org >> > >> <mailto:GoldenS at njhealth.org>> wrote: >> > >> Hi all, >> > >> >> > >> I have been attempting to access the source code for the keyword >> > >> ?function? to better understand how it assigns and stores logical inputs, >> > >> like in the subset() [base] function. Does anyone know how I can access the >> > >> source code for this? >> > >> >> > >> For example, if I have >> > >> norm <- function(x){ >> > >> sqrt(x%*%x)) >> > >> } >> > >> I am looking for the source code for the ?function? portion, highlighted >> > >> in red. >> > >> >> > >> Thank you for your time and assistance, >> > >> Shelby Golden >> > >> Lab Researcher Technician >> > >> Dr. Russell Bowler?s Lab >> > >> Department of Medicine >> > >> National Jewish Health in Denver, CO >> > >> Phone: (303) 270-2598 >> > >> >> > >> NOTICE: This email message is for the sole use of the intended >> > >> recipient(s) and may contain confidential and privileged information. Any >> > >> unauthorized review, use, disclosure or distribution is prohibited. If you >> > >> are not the intended recipient, please contact the sender by reply email >> > >> and destroy all copies of the original message. >> > >> [[alternative HTML version deleted]] >> > >> >> > >> ______________________________________________ >> > >> R-help at r-project.org<mailto:R-help at r-project.org> mailing list -- To >> > >> UNSUBSCRIBE and more, see >> > >> https://stat.ethz.ch/mailman/listinfo/r-help< >> > >> http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZmMWRiYmMxZjFmNmI5ZDBkMz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJjljNzlmMDA4YWRmZTZjMz0xMjMzJiZ1cmw9aHR0cHMlM0ElMkYlMkZzdGF0JTJFZXRoeiUyRWNoJTJGbWFpbG1hbiUyRmxpc3RpbmZvJTJGci1oZWxw >> > >> > >> > >> PLEASE do read the posting guide >> > >> http://www.R-project.org/posting-guide.html< >> > >> http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZlMTkwYmMwMzFlNjk4ZTAzNz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJmFkYTkxMWRkMWRhZTFkNz0xMjMzJiZ1cmw9aHR0cCUzQSUyRiUyRnd3dyUyRVItcHJvamVjdCUyRW9yZyUyRnBvc3RpbmctZ3VpZGUlMkVodG1s >> > >> > >> > >> and provide commented, minimal, self-contained, reproducible code. >> > >> >> > >> [[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 >> > >> http://www.R-project.org/posting-guide.html >> > >> and provide commented, minimal, self-contained, reproducible code. >> > >> >> > > >> > >> > [[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 http://www.R-project.org/posting-guide.html >> > and provide commented, minimal, self-contained, reproducible code. >> ______________________________________________ >> 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 http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> >> >> NOTICE: This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. >> ______________________________________________ >> 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 http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > 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 http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.-- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
> I am looking to understand why the keyword function can take a logicalargument> (eg: x<4) and use that later inside the function's definition for logicalevaluations The "function" keyword does not take a logical argument. Let me show you some parallels: f <- function (x, y) {x+y} # R (set! f (lambda (x y) (+ x y))) ; Scheme f = (x, y) => { return x+y; }; // Javascript f = (x, y) => { return x+y; }; // C#, given a suitable declaration for f f = (x, y) -> { return x+y; } // Java, given a suitable declaration for f. lambda x y; x+y end -> f; // Pop-2, older than the others. In all of these, - there is something ('function', 'lambda', '=>', '->') that says "here is an anonymous function" - there is a list of zero or more parameters - there is a body which may contain statements and may also return a result. The keyword in itself does nothing. The compiler recognises the construction and generates code for a procedure that is bound to the environment where it is created, so that it can find variables other than those in its parameter list. When it comes to passing parameters to a function, there is nothing special about logical expressions in any of these languages. Now there *is* something about functions in R that is special. The S language (which R is based on) is the only one I am familiar with that combines two properties: - it is an imperative language with side effects to variables - it does not evaluate function arguments when they are passed but when they are first *used*. An obvious reason for this is to allow plotting methods to construct labels from their arguments and to allow model fitting methods to remember the form of the model. If you want argument evaluation delayed for any other reason, it is probably better to pass a function. See> ?integrate-- the first argument is a function, not a general expression> ?optim-- the second argument is a function, not a general expression (That is, the argument in question is an expression whose value must be a function, not an expression to be manipulated *textually* or as a formula.) On Sat, 7 Sep 2019 at 08:07, Golden, Shelby <GoldenS at njhealth.org> wrote:> Thank you all for your reply. I should clarify, that I am looking to > understand why the keyword function can take a logical argument (eg: x<4) > and use that later inside the function's definition for logical evaluations. > > Consider this example, which is a simplification of > getAnywhere(subset.data.frame): > x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" = c(6, 7, 8, 9, 10)) > test <- function(x, logic){ > e <- substitute(logic) > r <- eval(e, x, parent.frame()) > r[r] > } > > > Shelby > > > ?On 9/6/19, 1:02 PM, "R-help on behalf of Richard M. Heiberger" < > r-help-bounces at r-project.org on behalf of rmh at temple.edu> wrote: > > You might also want to look at the codetools package, for example the > showTree function " Prints a Lisp-style representation of R > expression." > > > library(codetools) > > > showTree(quote(x %*% x)) > (%*% x x) > > showTree(quote(a+b)) > (+ a b) > > showTree(quote(y ~ a+b)) > (~ y (+ a b)) > > On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at gmail.com> > wrote: > > > > The following may be of use (it gives the parse tree of the text): > > > > > z <- as.list(parse(text = "function(x)x %*% x")) > > > z[[1]] > > function(x) x %*% x > > > z[[c(1,1)]] > > `function` > > > z[[c(1,2)]] > > $x > > > z[[c(1,3)]] > > x %*% x > > > z[[c(1,3,1)]] > > `%*%` > > > z[[c(1,3,2)]] > > x > > > z[[c(1,3,3)]] > > x > > > > > > Bert Gunter > > > > > > > > On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at gmail.com> > wrote: > > > > > If you are looking for an R code parser, I think the `parse` and > `eval` > > > function might be a good start point. See the example below. > > > > > > > parse(text="function(x)message(x)") > > > expression(function(x)message(x)) > > > > eval(parse(text="function(x)message(x)")) > > > function(x)message(x) > > > > > > Best, > > > Jiefei > > > > > > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby < > GoldenS at njhealth.org> > > > wrote: > > > > > >> Hello Bert, > > >> > > >> Thank you for the reply and your clarifications. Yes, it might be > helpful > > >> to look into R?s formal grammar to see how ?function? parses > input to > > >> delegate correct syntax. Is that accessible online? > > >> > > >> Thank you, > > >> Shelby > > >> > > >> > > >> From: Bert Gunter <bgunter.4567 at gmail.com> > > >> Date: Friday, September 6, 2019 at 10:44 AM > > >> To: "Golden, Shelby" <GoldenS at NJHealth.org> > > >> Cc: "r-help at R-project.org" <r-help at r-project.org>, "Gillenwater, > Lucas" < > > >> GILLENWATERL at NJHEALTH.ORG> > > >> Subject: Re: [R] [R-devel] Source Code for function > > >> > > >> 1. This is a plain text list; all html is stripped. So there is > no red > > >> highlighting. > > >> > > >> 2. There is no "source code" for "function" -- it is a reserved > keyword. > > >> Or are you looking for R's formal grammar -- e.g. how it parses > input to > > >> determine correct syntax? > > >> > > >> > > >> > > >> Bert Gunter > > >> > > >> "The trouble with having an open mind is that people keep coming > along > > >> and sticking things into it." > > >> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > >> > > >> > > >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby < > GoldenS at njhealth.org > > >> <mailto:GoldenS at njhealth.org>> wrote: > > >> Hi all, > > >> > > >> I have been attempting to access the source code for the keyword > > >> ?function? to better understand how it assigns and stores logical > inputs, > > >> like in the subset() [base] function. Does anyone know how I can > access the > > >> source code for this? > > >> > > >> For example, if I have > > >> norm <- function(x){ > > >> sqrt(x%*%x)) > > >> } > > >> I am looking for the source code for the ?function? portion, > highlighted > > >> in red. > > >> > > >> Thank you for your time and assistance, > > >> Shelby Golden > > >> Lab Researcher Technician > > >> Dr. Russell Bowler?s Lab > > >> Department of Medicine > > >> National Jewish Health in Denver, CO > > >> Phone: (303) 270-2598 > > >> > > >> NOTICE: This email message is for the sole use of the intended > > >> recipient(s) and may contain confidential and privileged > information. Any > > >> unauthorized review, use, disclosure or distribution is > prohibited. If you > > >> are not the intended recipient, please contact the sender by > reply email > > >> and destroy all copies of the original message. > > >> [[alternative HTML version deleted]] > > >> > > >> ______________________________________________ > > >> R-help at r-project.org<mailto:R-help at r-project.org> mailing list > -- To > > >> UNSUBSCRIBE and more, see > > >> https://stat.ethz.ch/mailman/listinfo/r-help< > > >> > http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZmMWRiYmMxZjFmNmI5ZDBkMz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJjljNzlmMDA4YWRmZTZjMz0xMjMzJiZ1cmw9aHR0cHMlM0ElMkYlMkZzdGF0JTJFZXRoeiUyRWNoJTJGbWFpbG1hbiUyRmxpc3RpbmZvJTJGci1oZWxw > > >> > > > >> PLEASE do read the posting guide > > >> http://www.R-project.org/posting-guide.html< > > >> > http://mx2.njhealth.org:32224/?dmVyPTEuMDAxJiZlMTkwYmMwMzFlNjk4ZTAzNz01RDcyOEQwN18yMjk2OF8zOTk2XzEmJmFkYTkxMWRkMWRhZTFkNz0xMjMzJiZ1cmw9aHR0cCUzQSUyRiUyRnd3dyUyRVItcHJvamVjdCUyRW9yZyUyRnBvc3RpbmctZ3VpZGUlMkVodG1s > > >> > > > >> and provide commented, minimal, self-contained, reproducible code. > > >> > > >> [[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 > > >> http://www.R-project.org/posting-guide.html > > >> and provide commented, minimal, self-contained, reproducible code. > > >> > > > > > > > [[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 > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > 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 > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > > > NOTICE: This email message is for the sole use of the intended > recipient(s) and may contain confidential and privileged information. Any > unauthorized review, use, disclosure or distribution is prohibited. If you > are not the intended recipient, please contact the sender by reply email > and destroy all copies of the original message. > ______________________________________________ > 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 > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
Wow, this is great! Thank you, Richard, for going so in-depth with this explanation. My ultimate goal is to create a vector that stores logical evaluations to be used later in a function that subsets data. I?ve coded multiple projects, now, that require this kind of sub-setting across multiple unique logical evaluations. So, streamlining the in-put and the out-put is ideal to minimize error and generalize my code. I will look further into this information to see if it can help me get around using parse(text = )), which, to my understanding, is not a good coding method (https://stackoverflow.com/questions/1743698/evaluate-expression-given-as-a-string - comment left Martin Maechler). Thank you again, and I hope you have a wonderful week! Shelby From: Richard O'Keefe <raoknz at gmail.com> Date: Sunday, September 8, 2019 at 11:01 PM To: "Golden, Shelby" <GoldenS at NJHealth.org> Cc: "Richard M. Heiberger" <rmh at temple.edu>, Bert Gunter <bgunter.4567 at gmail.com>, "r-help at R-project.org" <r-help at r-project.org>, "Gillenwater, Lucas" <GILLENWATERL at NJHEALTH.ORG> Subject: Re: [R] [R-devel] Source Code for function> I am looking to understand why the keyword function can take a logical argument > (eg: x<4) and use that later inside the function's definition for logical evaluationsThe "function" keyword does not take a logical argument. Let me show you some parallels: f <- function (x, y) {x+y} # R (set! f (lambda (x y) (+ x y))) ; Scheme f = (x, y) => { return x+y; }; // Javascript f = (x, y) => { return x+y; }; // C#, given a suitable declaration for f f = (x, y) -> { return x+y; } // Java, given a suitable declaration for f. lambda x y; x+y end -> f; // Pop-2, older than the others. In all of these, - there is something ('function', 'lambda', '=>', '->') that says "here is an anonymous function" - there is a list of zero or more parameters - there is a body which may contain statements and may also return a result. The keyword in itself does nothing. The compiler recognises the construction and generates code for a procedure that is bound to the environment where it is created, so that it can find variables other than those in its parameter list. When it comes to passing parameters to a function, there is nothing special about logical expressions in any of these languages. Now there *is* something about functions in R that is special. The S language (which R is based on) is the only one I am familiar with that combines two properties: - it is an imperative language with side effects to variables - it does not evaluate function arguments when they are passed but when they are first *used*. An obvious reason for this is to allow plotting methods to construct labels from their arguments and to allow model fitting methods to remember the form of the model. If you want argument evaluation delayed for any other reason, it is probably better to pass a function. See> ?integrate-- the first argument is a function, not a general expression> ?optim-- the second argument is a function, not a general expression (That is, the argument in question is an expression whose value must be a function, not an expression to be manipulated *textually* or as a formula.) On Sat, 7 Sep 2019 at 08:07, Golden, Shelby <GoldenS at njhealth.org<mailto:GoldenS at njhealth.org>> wrote: Thank you all for your reply. I should clarify, that I am looking to understand why the keyword function can take a logical argument (eg: x<4) and use that later inside the function's definition for logical evaluations. Consider this example, which is a simplification of getAnywhere(subset.data.frame): x = data.frame("Col1" = c(1, 2, 3, 4, 5), "Col2" = c(6, 7, 8, 9, 10)) test <- function(x, logic){ e <- substitute(logic) r <- eval(e, x, parent.frame()) r[r] } Shelby On 9/6/19, 1:02 PM, "R-help on behalf of Richard M. Heiberger" <r-help-bounces at r-project.org<mailto:r-help-bounces at r-project.org> on behalf of rmh at temple.edu<mailto:rmh at temple.edu>> wrote: You might also want to look at the codetools package, for example the showTree function " Prints a Lisp-style representation of R expression." > library(codetools) > showTree(quote(x %*% x)) (%*% x x) > showTree(quote(a+b)) (+ a b) > showTree(quote(y ~ a+b)) (~ y (+ a b)) On Fri, Sep 6, 2019 at 2:30 PM Bert Gunter <bgunter.4567 at gmail.com<mailto:bgunter.4567 at gmail.com>> wrote: > > The following may be of use (it gives the parse tree of the text): > > > z <- as.list(parse(text = "function(x)x %*% x")) > > z[[1]] > function(x) x %*% x > > z[[c(1,1)]] > `function` > > z[[c(1,2)]] > $x > > z[[c(1,3)]] > x %*% x > > z[[c(1,3,1)]] > `%*%` > > z[[c(1,3,2)]] > x > > z[[c(1,3,3)]] > x > > > Bert Gunter > > > > On Fri, Sep 6, 2019 at 10:14 AM Wang Jiefei <szwjf08 at gmail.com<mailto:szwjf08 at gmail.com>> wrote: > > > If you are looking for an R code parser, I think the `parse` and `eval` > > function might be a good start point. See the example below. > > > > > parse(text="function(x)message(x)") > > expression(function(x)message(x)) > > > eval(parse(text="function(x)message(x)")) > > function(x)message(x) > > > > Best, > > Jiefei > > > > On Fri, Sep 6, 2019 at 12:55 PM Golden, Shelby <GoldenS at njhealth.org<mailto:GoldenS at njhealth.org>> > > wrote: > > > >> Hello Bert, > >> > >> Thank you for the reply and your clarifications. Yes, it might be helpful > >> to look into R?s formal grammar to see how ?function? parses input to > >> delegate correct syntax. Is that accessible online? > >> > >> Thank you, > >> Shelby > >> > >> > >> From: Bert Gunter <bgunter.4567 at gmail.com<mailto:bgunter.4567 at gmail.com>> > >> Date: Friday, September 6, 2019 at 10:44 AM > >> To: "Golden, Shelby" <GoldenS at NJHealth.org> > >> Cc: "r-help at R-project.org" <r-help at r-project.org<mailto:r-help at r-project.org>>, "Gillenwater, Lucas" < > >> GILLENWATERL at NJHEALTH.ORG<mailto:GILLENWATERL at NJHEALTH.ORG>> > >> Subject: Re: [R] [R-devel] Source Code for function > >> > >> 1. This is a plain text list; all html is stripped. So there is no red > >> highlighting. > >> > >> 2. There is no "source code" for "function" -- it is a reserved keyword. > >> Or are you looking for R's formal grammar -- e.g. how it parses input to > >> determine correct syntax? > >> > >> > >> > >> Bert Gunter > >> > >> "The trouble with having an open mind is that people keep coming along > >> and sticking things into it." > >> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > >> > >> > >> On Fri, Sep 6, 2019 at 8:51 AM Golden, Shelby <GoldenS at njhealth.org<mailto:GoldenS at njhealth.org> > >> <mailto:GoldenS at njhealth.org<mailto:GoldenS at njhealth.org>>> wrote: > >> Hi all, > >> > >> I have been attempting to access the source code for the keyword > >> ?function? to better understand how it assigns and stores logical inputs, > >> like in the subset() [base] function. Does anyone know how I can access the > >> source code for this? > >> > >> For example, if I have > >> norm <- function(x){ > >> sqrt(x%*%x)) > >> } > >> I am looking for the source code for the ?function? portion, highlighted > >> in red. > >> > >> Thank you for your time and assistance, > >> Shelby Golden > >> Lab Researcher Technician > >> Dr. Russell Bowler?s Lab > >> Department of Medicine > >> National Jewish Health in Denver, CO > >> Phone: (303) 270-2598 > >> > >> NOTICE: This email message is for the sole use of the intended > >> recipient(s) and may contain confidential and privileged information. Any > >> unauthorized review, use, disclosure or distribution is prohibited. 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