R help - Sep 2009 - Re ading Functions that are in a Vector

I am trying to write a function that will have an input of a vector of
functions. Here is a simplistic example.
sumstats <- c(mean,sd)
sumstats[1]
#Gives this error
#> sumstats[1]
#[[1]]
#function (x, ...) 
#UseMethod("mean")
#<environment: namespace:base>

I thought about restricting the input to character variables such as the
following
sumstats2 <- c("mean","sd")
Is there a way to change "mean" to the function mean?
-- 
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On Sun, Sep 27, 2009 at 10:36 PM, trumpetsaz <stephaniezimmer at
gmail.com> wrote:
>
> I am trying to write a function that will have an input of a vector of
> functions. Here is a simplistic example.
> sumstats <- c(mean,sd)
> sumstats[1]
> #Gives this error
> #> sumstats[1]
> #[[1]]
> #function (x, ...)
> #UseMethod("mean")
> #<environment: namespace:base>
That's not an error.  The code asked it to return the first function
so that's what it did.
>
> I thought about restricting the input to character variables such as the
> following
> sumstats2 <- c("mean","sd")
> Is there a way to change "mean" to the function mean?
This gives a vector of functions given a vector of their names:

 sumstat1 <- lapply(sumstats2, get)

On 28/09/2009, at 3:36 PM, trumpetsaz wrote:
>
> I am trying to write a function that will have an input of a vector of
> functions. Here is a simplistic example.
> sumstats <- c(mean,sd)
> sumstats[1]
> #Gives this error
> #> sumstats[1]
> #[[1]]
> #function (x, ...)
> #UseMethod("mean")
> #<environment: namespace:base>
>
> I thought about restricting the input to character variables such  
> as the
> following
> sumstats2 <- c("mean","sd")
> Is there a way to change "mean" to the function mean?
You *can't* have a vector of functions, as far I know.  The entries
of a vector must be (numeric, character, or logical) scalars.

You *can* have a *list* of functions; this might be the way you
want to go.

To ``change "mean" to the function mean'' --- set ?get.

	cheers,

		Rolf Turner

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Hi,

You said,
>sumstats <- c(mean,sd)
>sumstats[1]
>#Gives this error
but this is not an error! You created a list that contains two
functions, and sumstats[1] simply prints the first one.

HTH,

baptiste

Also, have a look at each() in the plyr package,

library(plyr)
each(length, mean, var)(rnorm(100))


baptiste

2009/9/28 trumpetsaz <stephaniezimmer at
gmail.com>:
>
> I am trying to write a function that will have an input of a vector of
> functions. Here is a simplistic example.
> sumstats <- c(mean,sd)
> sumstats[1]
> #Gives this error
> #> sumstats[1]
> #[[1]]
> #function (x, ...)
> #UseMethod("mean")
> #<environment: namespace:base>
>
> I thought about restricting the input to character variables such as the
> following
> sumstats2 <- c("mean","sd")
> Is there a way to change "mean" to the function mean?
> --
> View this message in context:
http://www.nabble.com/Reading-Functions-that-are-in-a-Vector-tp25639720p25639720.html
> Sent from the R help mailing list archive at Nabble.com.
>
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