Re: [Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
On Nov 19, 2011, at 04:35 , Henrik Bengtsson wrote: On Fri, Nov 18, 2011 at 9:34 AM, Kevin R. Coombes kevin.r.coom...@gmail.com wrote: You can also see the odd behavior without wrapping round in another function: round(100.1, digits=) [1] 100 Hmm... is there a reason for why the parser accepts that construct? Yes. See e.g. help(alist) for actual usage. It can also be used to pass empty arguments to FUN in apply-constructs: a - matrix(1:12, 3, 4) f - function(i, j) a[i,j] lapply(1:4, f, i=) Some example: parse(text=f(a=)) expression(f(a=)) parse(text=f[a=]) expression(f[a=]) parse(text=(a=)) Error in parse.default(text = (a=)) : text:1:4: unexpected ')' 1: (a=) /Henrik On 11/18/2011 10:19 AM, Joris Meys wrote: On Fri, Nov 18, 2011 at 5:10 PM, Gavin Simpsongavin.simp...@ucl.ac.uk wrote: round is indicated to not evaluate its arguments. I don't follow the C code well enough to know if it should be catching the missing argument further on - it must be because it is falling back to the default, but the above explains that the not evaluating arguments is intended. G So if I understand it right, the y argument is not evaluated in the fun2 function but deeper in the C code. that explains the lack of the error message, thanks! I keep on learning every day. Cheers Joris __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd@cbs.dk Priv: pda...@gmail.com __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
I have stumbled across some behaviour in R that I really can't place,
and that makes coding a bit tricky. I know that I can work around it
when explicitly checking for missing arguments, but still...
I have two functions. I have a first function based on paste
fun1 - function(x,y){
print(missing(y))
paste(x,'X',sep=y)
}
If I try this function without specifying `y`, I get the (expected)
error message:
fun1(letters[1:6])
[1] TRUE
Error in paste(x, X, sep = y) :
argument y is missing, with no default
The second one with round :
fun2 - function(x,y){ print(missing(y)) round(x,digits=y) }
If I try this function without specifying `y`, it works unexpectedly
whereas it shouldn't :
fun2(100.1) [1] TRUE [1] 100
In my view, fun1 should definitely give the error message as well, as
it is not intended to have a default behaviour when y is missing.
Still, the round() function ignores the fact y is missing. Is this by
design, is there a check missing in round, or is something else going
on that I am overlooking?
Cheers
Joris
sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: i386-pc-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=English_United Kingdom.1252
[2] LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods
[7] base
loaded via a namespace (and not attached):
[1] tools_2.14.0
--
Joris Meys
Statistical consultant
Ghent University
Faculty of Bioscience Engineering
Department of Mathematical Modelling, Statistics and Bio-Informatics
tel : +32 9 264 59 87
joris.m...@ugent.be
---
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
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Re: [Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
On Nov 18, 2011, at 10:43 AM, Joris Meys wrote:
I have stumbled across some behaviour in R that I really can't place,
and that makes coding a bit tricky. I know that I can work around it
when explicitly checking for missing arguments, but still...
I have two functions. I have a first function based on paste
fun1 - function(x,y){
print(missing(y))
paste(x,'X',sep=y)
}
If I try this function without specifying `y`, I get the (expected)
error message:
fun1(letters[1:6])
[1] TRUE
Error in paste(x, X, sep = y) :
argument y is missing, with no default
The second one with round :
fun2 - function(x,y){ print(missing(y)) round(x,digits=y)}
If I try this function without specifying `y`, it works unexpectedly
whereas it shouldn't :
fun2(100.1)[1] TRUE[1] 100
In my view, fun1 should definitely give the error message as well, as
it is not intended to have a default behaviour when y is missing.
Still, the round() function ignores the fact y is missing. Is this by
design, is there a check missing in round, or is something else going
on that I am overlooking?
round
function (x, digits = 0) .Primitive(round)
it has a default so it is fine for digits to be missing since it will have
value 0 in that case ...
Cheers,
S
Cheers
Joris
sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: i386-pc-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=English_United Kingdom.1252
[2] LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods
[7] base
loaded via a namespace (and not attached):
[1] tools_2.14.0
--
Joris Meys
Statistical consultant
Ghent University
Faculty of Bioscience Engineering
Department of Mathematical Modelling, Statistics and Bio-Informatics
tel : +32 9 264 59 87
joris.m...@ugent.be
---
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
__
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
__
R-devel@r-project.org mailing list
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Re: [Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
On Fri, 2011-11-18 at 16:43 +0100, Joris Meys wrote:
I have stumbled across some behaviour in R that I really can't place,
and that makes coding a bit tricky. I know that I can work around it
when explicitly checking for missing arguments, but still...
I have two functions. I have a first function based on paste
fun1 - function(x,y){
print(missing(y))
paste(x,'X',sep=y)
}
If I try this function without specifying `y`, I get the (expected)
error message:
fun1(letters[1:6])
[1] TRUE
Error in paste(x, X, sep = y) :
argument y is missing, with no default
The second one with round :
fun2 - function(x,y){ print(missing(y)) round(x,digits=y)}
If I try this function without specifying `y`, it works unexpectedly
whereas it shouldn't :
fun2(100.1)[1] TRUE[1] 100
round() is implemented as:
round
function (x, digits = 0) .Primitive(round)
using the .Primitive means of calling C code. `?.Primitve` refers you to
the R Internals manual, which basically states that how the compiled
functions should be called and number of arguments etc is stored in a
table. This table is given here:
http://svn.r-project.org/R/trunk/src/main/names.c
The relevant part of which is:
/* printnamec-entry offset evalarity pp-kind precedence
rightassoc
* ---- -- - --- --
--*/
/* Mathematical Functions */
/* primitives: these are group generic and so need to eval args (possibly
internally) */
{round, do_Math2, 10001, 0, -1, {PP_FUNCALL, PREC_FN,
0}},
the eval column indicates features of how arguments are evaluated and
what have you. A value of 0 equates to 000 and the last 0 indicates
whether arguments are to be evaluated with 0 indicating no evaluation
and 1 evaluation.
round is indicated to not evaluate its arguments. I don't follow the C
code well enough to know if it should be catching the missing argument
further on - it must be because it is falling back to the default, but
the above explains that the not evaluating arguments is intended.
G
In my view, fun1 should definitely give the error message as well, as
it is not intended to have a default behaviour when y is missing.
Still, the round() function ignores the fact y is missing. Is this by
design, is there a check missing in round, or is something else going
on that I am overlooking?
Cheers
Joris
sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: i386-pc-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=English_United Kingdom.1252
[2] LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods
[7] base
loaded via a namespace (and not attached):
[1] tools_2.14.0
--
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
Dr. Gavin Simpson [t] +44 (0)20 7679 0522
ECRC, UCL Geography, [f] +44 (0)20 7679 0565
Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk
Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/
UK. WC1E 6BT. [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
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Re: [Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
You can also see the odd behavior without wrapping round in another function: round(100.1, digits=) [1] 100 On 11/18/2011 10:19 AM, Joris Meys wrote: On Fri, Nov 18, 2011 at 5:10 PM, Gavin Simpsongavin.simp...@ucl.ac.uk wrote: round is indicated to not evaluate its arguments. I don't follow the C code well enough to know if it should be catching the missing argument further on - it must be because it is falling back to the default, but the above explains that the not evaluating arguments is intended. G So if I understand it right, the y argument is not evaluated in the fun2 function but deeper in the C code. that explains the lack of the error message, thanks! I keep on learning every day. Cheers Joris __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] round() ignores missing arguments if it is used inside another function where some arguments are missing.
On Fri, Nov 18, 2011 at 9:34 AM, Kevin R. Coombes kevin.r.coom...@gmail.com wrote: You can also see the odd behavior without wrapping round in another function: round(100.1, digits=) [1] 100 Hmm... is there a reason for why the parser accepts that construct? Some example: parse(text=f(a=)) expression(f(a=)) parse(text=f[a=]) expression(f[a=]) parse(text=(a=)) Error in parse.default(text = (a=)) : text:1:4: unexpected ')' 1: (a=) /Henrik On 11/18/2011 10:19 AM, Joris Meys wrote: On Fri, Nov 18, 2011 at 5:10 PM, Gavin Simpsongavin.simp...@ucl.ac.uk wrote: round is indicated to not evaluate its arguments. I don't follow the C code well enough to know if it should be catching the missing argument further on - it must be because it is falling back to the default, but the above explains that the not evaluating arguments is intended. G So if I understand it right, the y argument is not evaluated in the fun2 function but deeper in the C code. that explains the lack of the error message, thanks! I keep on learning every day. Cheers Joris __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
