R devel - Jan 2014 - formals() adds 0 to complex function arguments

Dear list,

I'm facing an issue with the automated documentation of a function using
roxygen2. The function has a complex-valued default argument, which is
picked up by roxygen2 using formals() to generate the corresponding Usage
section of the Rd file. Unfortunately, it appears that formals() reformats
complex numbers. Consider the example below,

test <- function(a = 1+2i){}
> args(test)
function (a = 1 + (0+2i))
  NULL
> formals(test)
$a
1 + (0+2i)

As a result, R CMD check issues a warning that my Rd file is inconsistent
between Code and Docs. Redefining the function with this syntax (a = 1 +
(0+2i)) doesn't help, as a new 0 gets added to become 1 + (0 + (0+2i)).

Is this reformatting necessary?

Regards,

baptiste

sessionInfo()
R Under development (unstable) (2013-11-25 r64299)
Platform: x86_64-apple-darwin10.8.0 (64-bit)

locale:
[1] en_NZ.UTF-8/en_NZ.UTF-8/en_NZ.UTF-8/C/en_NZ.UTF-8/en_NZ.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] tools_3.1.0

	[[alternative HTML version deleted]]

It's not formals() that is doing you in. Rather, it is a conspiration
between two things:
(a) R always displays complex constants as x+yi, even if x is zero and (b) there
really is no way to specify complex constants with non-zero  real part, i.e.
1+2i is a sum of a real and and imaginary complex constant. You can see the
effect already at
> quote(1+2i)
1 + (0+2i)

> q <- quote(1+2i)
> q[[1]]
`+`
> q[[2]]
[1] 1
> q[[3]]
[1] 0+2i
> str(q)
 language 1 + (0+2i)
> str(q[[3]])
 cplx 0+2i

Someone might want to fix this by implementing a full syntax for complex
constants, but meanwhile, I think a passable workaround could be
> formals(test)$a <- 1+2i
> args(test)
function (a = 1+2i) 
NULL
> test
function (a = 1+2i) 
{
}


Or maybe, less sneaky

Cplx_1plus2i <- 1+2i
test <- function(a = Cplx_1plus2i){}

-pd 


On 19 Jan 2014, at 20:45 , baptiste auguie <baptiste.auguie at gmail.com>
wrote:
> Dear list,
> 
> I'm facing an issue with the automated documentation of a function
using
> roxygen2. The function has a complex-valued default argument, which is
> picked up by roxygen2 using formals() to generate the corresponding Usage
> section of the Rd file. Unfortunately, it appears that formals() reformats
> complex numbers. Consider the example below,
> 
> test <- function(a = 1+2i){}
> 
>> args(test)
> function (a = 1 + (0+2i))
>  NULL
>> formals(test)
> $a
> 1 + (0+2i)
> 
> As a result, R CMD check issues a warning that my Rd file is inconsistent
> between Code and Docs. Redefining the function with this syntax (a = 1 +
> (0+2i)) doesn't help, as a new 0 gets added to become 1 + (0 + (0+2i)).
> 
> Is this reformatting necessary?
> 
> Regards,
> 
> baptiste
> 
> sessionInfo()
> R Under development (unstable) (2013-11-25 r64299)
> Platform: x86_64-apple-darwin10.8.0 (64-bit)
> 
> locale:
> [1] en_NZ.UTF-8/en_NZ.UTF-8/en_NZ.UTF-8/C/en_NZ.UTF-8/en_NZ.UTF-8
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
> loaded via a namespace (and not attached):
> [1] tools_3.1.0
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel at 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.mes at cbs.dk  Priv: PDalgd at gmail.com