passing a vector of variable names to the ... pairlist function argument

Hi,

I have a character vector that contains the names of several objects
that I would like to pass to a function (specifically, the ridge
function in the survival package, but cbind is a similar example). I've
been struggling with how to do this so that the object values get
interpreted by the function, rather than the object names.

For example,
x1 <- 1:4
x2 <- 2:5
x3 <- 3:6
xs <- c("x1", "x2", "x3")

If I wanted to cbind(x1, x2, x3) without typing this out, how would I do
it?

Thanks very much!

Jessica Myers
Instructor in Medicine
Division of Pharmacoepidemiology
Brigham and Women's Hospital



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On 21.04.2011 16:03, Jessica Myers wrote:

Hi,

I have a character vector that contains the names of several objects
that I would like to pass to a function (specifically, the ridge
function in the survival package, but cbind is a similar example).  
I've
been struggling with how to do this so that the object values get
interpreted by the function, rather than the object names.

For example,
x1 <- 1:4
x2 <- 2:5
x3 <- 3:6
xs <- c("x1", "x2", "x3")

If I wanted to cbind(x1, x2, x3) without typing this out, how would  
I do
it?

For the cbind case, I'd omit cbind and ask R to:

 sapply(xs, get)

or

 apply(matrix(xs), 1, get)

or with cbind():

 do.call("cbind", lapply(xs, get))

the latter can be generalized for other function calls, of course.

Best,
Uwe Ligges

Thanks very much!

Jessica Myers
Instructor in Medicine
Division of Pharmacoepidemiology
Brigham and Women's Hospital



The information in this e-mail is intended only for t...{{dropped:19}}

Thanks - your last suggestion does seem to work with the ridge function,
but the names of the objects get lost in the process. Is there a way to
keep the object names with get?

Thanks,
Jessica Myers

On Apr 21, 2011, at 11:00 AM, Uwe Ligges wrote:

On 21.04.2011 16:03, Jessica Myers wrote:

Hi,

I have a character vector that contains the names of several objects
that I would like to pass to a function (specifically, the ridge
function in the survival package, but cbind is a similar example). I've
been struggling with how to do this so that the object values get
interpreted by the function, rather than the object names.

For example,
x1 <- 1:4
x2 <- 2:5
x3 <- 3:6
xs <- c("x1", "x2", "x3")

If I wanted to cbind(x1, x2, x3) without typing this out, how would I do
it?

For the cbind case, I'd omit cbind and ask R to:

sapply(xs, get)

or

apply(matrix(xs), 1, get)

or with cbind():

do.call("cbind", lapply(xs, get))

the latter can be generalized for other function calls, of course.

Best,
Uwe Ligges

Thanks very much!

Jessica Myers
Instructor in Medicine
Division of Pharmacoepidemiology
Brigham and Women's Hospital



The information in this e-mail is intended only for the ...{{dropped:7}}

The information in this e-mail is intended only for th...{{dropped:13}}