# [R] Deparsing part of a list argument

Steven McKinney smckinney at bccrc.ca
Sat Oct 27 04:25:43 CEST 2007

```This is one way to implement the idea
the other responses point at:

> myfun <- function(funlist, vec){
+     tmp <- lapply(funlist, function(x)do.call(x, args = list(vec)))
+     names(tmp)[names(tmp) == ""] <-
+       sapply(match.call()[], deparse)[-1][names(tmp) == ""]
+     tmp
+ }
>

>
> myfun(list("Summation" = sum, prod, "Absolute value" = abs), c(1, 4, 6,
+ 7))
\$Summation
 18

\$prod
 168

\$`Absolute value`
 1 4 6 7

Steven McKinney

Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre

email: smckinney +at+ bccrc +dot+ ca

tel: 604-675-8000 x7561

BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C.
V5Z 1L3

-----Original Message-----
From: r-help-bounces at r-project.org on behalf of Andrew Smith
Sent: Thu 10/25/2007 2:38 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Deparsing part of a list argument

Here's a simple example of the type of function I'm trying to write,
where the first argument is a list of functions:

myfun <- function(funlist, vec){
tmp <- lapply(funlist, function(x)do.call(x, args = list(vec)))
names(tmp) <- names(funlist)
tmp
}

> myfun(list("Summation" = sum, prod, "Absolute value" = abs), c(1, 4, 6, 7))
\$Summation
 18

[]
 168

\$`Absolute value`
 1 4 6 7

What I would like is for the names of the result to be the same as the
names of funlist (as is the case in components 1 and 3 above), but if
some components of funlist are unnamed, I would like the default name
in the result to be the name of the actual function used.  So in the
above example, I want the name of the second component to default to
'prod', since funlist[] has no name.

But the problem is that I can't get the function names corresponding
to the unnamed elements of funlist by using the usual
deparse(substitute)) trick, since they're part of a list which is
treated as one big argument.  So deparse(substitute(funlist)) just
gives me one big character string of all the functions, and I'm not
sure how I can use that to get just the functions that aren't named.
Any ideas?

Thanks,
Andrew

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