[R] using argument names (of indeterminate number) within a function
Although I tried to find an answer in the manuals and archives, I cannot
solve this (please excuse that my English and/or R programming skills
are not good enough to state my problem more clearly):
I want to write a function with an indeterminate (not pre-defined)
number of arguments and think that I should use the ... construct and
the match.call() function. The goal is to write a function that (among
other things) uses cbind() to combine a not pre-defined number of
vectors specified in the function call. For example, if my vectors are
x1, x2, x3, ... xn, within the function I want to use cbind(x1, x2) or
cbind(x1, x3, x5) or ... depending on the vector names I use in the
funcion call. Additionally, the function has other arguments.
In the archives I found the following thread (followed by Marc Schwartz)
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/15186.html
[R] returning argument names from Peter Dalgaard BSA on 2003-04-10 (stdin)
that seems to contain the solution to my problem, but I am stuck because
sapply(match.call()[-1], deparse) gives me a vector of strings and I
don't know how to use the names in this vector in the cbind() function.
Up to now my (clearly deficit) function looks like:
test - function(..., mvalid=1)
{
args = sapply(match.call()[-1], deparse)
# and here, I don't know how the vector names in args
# can be used in the cbind() function to follow:
#
# temp - cbind( ???
if (mvalid 1)
{
# here it goes on
}
}
Ultimately, I want that the function can be called like
test(x1,x2,mvalid=1)
or
test(x1,x3,x5,mavlid=2)
and that within the function
cbind(x1,x2)
or cbind(x1,x3,x5)
will be used.
Can someone give and explain an example / a solution on how to proceed?
*
Dr. Dirk Enzmann
Institute of Criminal Sciences
Dept. of Criminology
Edmund-Siemers-Allee 1
D-20146 Hamburg
Germany
phone: +49-040-42838.7498 (office)
+49-040-42838.4591 (Billon)
fax: +49-040-42838.2344
email: [EMAIL PROTECTED]
www:
http://www2.jura.uni-hamburg.de/instkrim/kriminologie/Mitarbeiter/Enzmann/Enzmann.html
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] using argument names (of indeterminate number) within a function
On Tue, 2005-07-19 at 17:29 +0200, Dirk Enzmann wrote:
Although I tried to find an answer in the manuals and archives, I cannot
solve this (please excuse that my English and/or R programming skills
are not good enough to state my problem more clearly):
I want to write a function with an indeterminate (not pre-defined)
number of arguments and think that I should use the ... construct and
the match.call() function. The goal is to write a function that (among
other things) uses cbind() to combine a not pre-defined number of
vectors specified in the function call. For example, if my vectors are
x1, x2, x3, ... xn, within the function I want to use cbind(x1, x2) or
cbind(x1, x3, x5) or ... depending on the vector names I use in the
funcion call. Additionally, the function has other arguments.
In the archives I found the following thread (followed by Marc Schwartz)
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/15186.html
[R] returning argument names from Peter Dalgaard BSA on 2003-04-10 (stdin)
that seems to contain the solution to my problem, but I am stuck because
sapply(match.call()[-1], deparse) gives me a vector of strings and I
don't know how to use the names in this vector in the cbind() function.
Up to now my (clearly deficit) function looks like:
test - function(..., mvalid=1)
{
args = sapply(match.call()[-1], deparse)
# and here, I don't know how the vector names in args
# can be used in the cbind() function to follow:
#
# temp - cbind( ???
if (mvalid 1)
{
# here it goes on
}
}
Ultimately, I want that the function can be called like
test(x1,x2,mvalid=1)
or
test(x1,x3,x5,mavlid=2)
and that within the function
cbind(x1,x2)
or cbind(x1,x3,x5)
will be used.
Can someone give and explain an example / a solution on how to proceed?
Hi Dirk,
How about this:
my.cbind - function(...)
{
do.call(cbind, list(...))
}
a - 1:10
b - 11:20
c - 21:30
d - 31:40
my.cbind(a, b)
[,1] [,2]
[1,]1 11
[2,]2 12
[3,]3 13
[4,]4 14
[5,]5 15
[6,]6 16
[7,]7 17
[8,]8 18
[9,]9 19
[10,] 10 20
my.cbind(b, c, d)
[,1] [,2] [,3]
[1,] 11 21 31
[2,] 12 22 32
[3,] 13 23 33
[4,] 14 24 34
[5,] 15 25 35
[6,] 16 26 36
[7,] 17 27 37
[8,] 18 28 38
[9,] 19 29 39
[10,] 20 30 40
my.cbind(a, b, c, d)
[,1] [,2] [,3] [,4]
[1,]1 11 21 31
[2,]2 12 22 32
[3,]3 13 23 33
[4,]4 14 24 34
[5,]5 15 25 35
[6,]6 16 26 36
[7,]7 17 27 37
[8,]8 18 28 38
[9,]9 19 29 39
[10,] 10 20 30 40
The use of list(...) in the function allows you to use list based
functions such as do.call() or lapply() against the argument objects
directly without having to deparse and re-parse the character names of
the arguments, which is the approach that Peter used in his response in
the thread you referenced.
The OP in that thread wanted the argument names as character vectors, as
opposed to the argument objects themselves, which is what you need here.
HTH,
Marc Schwartz
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] using argument names (of indeterminate number) within a function
On 7/19/05, Dirk Enzmann [EMAIL PROTECTED] wrote:
Although I tried to find an answer in the manuals and archives, I cannot
solve this (please excuse that my English and/or R programming skills
are not good enough to state my problem more clearly):
I want to write a function with an indeterminate (not pre-defined)
number of arguments and think that I should use the ... construct and
the match.call() function. The goal is to write a function that (among
other things) uses cbind() to combine a not pre-defined number of
vectors specified in the function call. For example, if my vectors are
x1, x2, x3, ... xn, within the function I want to use cbind(x1, x2) or
cbind(x1, x3, x5) or ... depending on the vector names I use in the
funcion call. Additionally, the function has other arguments.
In the archives I found the following thread (followed by Marc Schwartz)
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/15186.html
[R] returning argument names from Peter Dalgaard BSA on 2003-04-10 (stdin)
that seems to contain the solution to my problem, but I am stuck because
sapply(match.call()[-1], deparse) gives me a vector of strings and I
don't know how to use the names in this vector in the cbind() function.
Up to now my (clearly deficit) function looks like:
test - function(..., mvalid=1)
{
args = sapply(match.call()[-1], deparse)
# and here, I don't know how the vector names in args
# can be used in the cbind() function to follow:
#
# temp - cbind( ???
if (mvalid 1)
{
# here it goes on
}
}
Ultimately, I want that the function can be called like
test(x1,x2,mvalid=1)
or
test(x1,x3,x5,mavlid=2)
and that within the function
cbind(x1,x2)
or cbind(x1,x3,x5)
will be used.
If you just need to pass them to cbind then just use cbind(...), e.g.
test - function(..., m) if (m 1) cbind(...) else m
otherwise, use list(...) as shown by a previous answer or here
test2 - function(..., m) if (m 1) length(list(...)) else m
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
