R help - Aug 2012 - how to coerce the result of sweep to be an array if result of FUN is a string?

Hi,

 

I would like to use sweep to "sweep out" proportions and confidence
intervals for an array, however when I supply a function which returns a string
(containing something like "9% (3-18%)") I get back a list instead of
an array, here is a simplified example:

 

# example showing that sweep does not return an array with same dimensions as
STATS as advertised

 

string.fun <- function(a, b) {

    paste(a, "-", b, sep="")

}

num.fun <- function(a, b) {

    a+b/100

}

m <- array(seq(1:24), dim = c(2,3,4))

stat <- array(seq(1:12), dim = c(3,4))

 

string.ans <- sweep(m, c(2,3), stat, string.fun)

dim(string.ans)

length(string.ans)

num.ans <- sweep(m, c(2,3), stat, num.fun)

dim(num.ans)

 

Although the contents are correct, strings.ans is a list while num.ans is an
array. Help(sweep) says that the result of sweep should have the same dimensions
as x, however when the result of the function is a string this is not the case. 
How can I coerce the result of the function to cause sweep to return an array as
advertised?

 

thanks,

Peter

 

Peter Young, MPH

Surveillance Epidemiologist

CDC Mozambique

 


	[[alternative HTML version deleted]]

Hello,

You can coerce the result to the input shape by assigning the dim 
attribute by hand.

string.ans <- sweep(m, c(2,3), stat, string.fun)
dim(string.ans) <- dim(m)
string.ans

Or put this in a function.

# An abbreviation and the complete function name
sweep.ch <- sweep.character <-
function(x, MARGIN, STATS, FUN="-", check.margin=TRUE, ...){
     result <- sweep(x, MARGIN, STATS, FUN, check.margin, ...)
     dim(result) <- dim(x)
     result
}

string.ans2 <- sweep.ch(m, c(2,3), stat, string.fun)
string.ans2


Hope this helps,

Rui Barradas

Em 04-08-2012 20:35, Peter Young escreveu:
> Hi,
>
>   
>
> I would like to use sweep to "sweep out" proportions and
confidence intervals for an array, however when I supply a function which
returns a string (containing something like "9% (3-18%)") I get back a
list instead of an array, here is a simplified example:
>
>   
>
> # example showing that sweep does not return an array with same dimensions
as STATS as advertised
>
>   
>
> string.fun <- function(a, b) {
>
>      paste(a, "-", b, sep="")
>
> }
>
> num.fun <- function(a, b) {
>
>      a+b/100
>
> }
>
> m <- array(seq(1:24), dim = c(2,3,4))
>
> stat <- array(seq(1:12), dim = c(3,4))
>
>   
>
> string.ans <- sweep(m, c(2,3), stat, string.fun)
>
> dim(string.ans)
>
> length(string.ans)
>
> num.ans <- sweep(m, c(2,3), stat, num.fun)
>
> dim(num.ans)
>
>   
>
> Although the contents are correct, strings.ans is a list while num.ans is
an array. Help(sweep) says that the result of sweep should have the same
dimensions as x, however when the result of the function is a string this is not
the case.  How can I coerce the result of the function to cause sweep to return
an array as advertised?
>
>   
>
> thanks,
>
> Peter
>
>   
>
> Peter Young, MPH
>
> Surveillance Epidemiologist
>
> CDC Mozambique
>
>   
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.