R help - Jan 2010 - tapply and more than one function, with different arguments

Dear R-users,

I am working with R version 2.10.1.

Say I have is a simple function like this:
> my.fun <- function(x, mult) mult*sum(x)
Now, I want to apply this function along with some other (say 'max') to
a simple data.frame, like:
> dat <- data.frame(x = 1:4, grp =
c("a","a","b","b"))
Ideally, the result would look something like this (if mult = 10):
  max my.fun
a   2     30
b   4     70

I have tried it that way:

apply.more.functions <- function(dat, FUN = c("max",
"my.fun"), ...) {
  res <- NULL
  for(f in FUN) res[[f]] <- tapply(dat$x, dat$grp, FUN = f, ...)
  data.frame(res)
}

# let's test it:
> apply.more.functions(dat, FUN = c("max", "min"))
  max min
a   2   1
b   4   3
# perfect!

# now, with an additional argument:
> apply.more.functions(dat, FUN = c("max", "my.fun"),
mult = 10)
  max my.fun
a  10     30
b  10     70
# uhuh!
Apparently, 'mult' has been used in the calculation of 'max' as
well.
How can I modify apply.more.functions in order to avoid this?

Your advice would be appreciated;
Kind regards
Heinrich.

Try replacing 'max' with 'mean' and see what you get.
Then have a look at ?max and see what max() does with
extra arguments.

I'm not sure it's relevant, but it might be useful
to check what Hmisc::summarize does.

  -Peter Ehlers

RINNER Heinrich wrote:
> Dear R-users,
> 
> I am working with R version 2.10.1.
> 
> Say I have is a simple function like this:
> 
>> my.fun <- function(x, mult) mult*sum(x)
> 
> Now, I want to apply this function along with some other (say
'max') to a simple data.frame, like:
> 
>> dat <- data.frame(x = 1:4, grp =
c("a","a","b","b"))
> 
> Ideally, the result would look something like this (if mult = 10):
>   max my.fun
> a   2     30
> b   4     70
> 
> I have tried it that way:
> 
> apply.more.functions <- function(dat, FUN = c("max",
"my.fun"), ...) {
>   res <- NULL
>   for(f in FUN) res[[f]] <- tapply(dat$x, dat$grp, FUN = f, ...)
>   data.frame(res)
> }
> 
> # let's test it:
>> apply.more.functions(dat, FUN = c("max", "min"))
>   max min
> a   2   1
> b   4   3
> # perfect!
> 
> # now, with an additional argument:
>> apply.more.functions(dat, FUN = c("max", "my.fun"),
mult = 10)
>   max my.fun
> a  10     30
> b  10     70
> # uhuh!
> Apparently, 'mult' has been used in the calculation of
'max' as well.
> How can I modify apply.more.functions in order to avoid this?
> 
> Your advice would be appreciated;
> Kind regards
> Heinrich.
> 
> ______________________________________________
> 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.
> 
> 
-- 
Peter Ehlers
University of Calgary

Hi:

Using the plyr package, we can get the result as follows:
> library(plyr)
> my.fun <- function(x, mult) mult*sum(x)
> dat <- data.frame(x = 1:4, grp =
c("a","a","b","b"))
> ddply(dat, .(grp), summarize, max = max(x), myfun = my.fun(x, 10))
  grp max myfun
1   a   2    30
2   b   4    70

HTH,
Dennis

On Tue, Jan 26, 2010 at 8:26 AM, RINNER Heinrich <
HEINRICH.RINNER@tirol.gv.at> wrote:
> Dear R-users,
>
> I am working with R version 2.10.1.
>
> Say I have is a simple function like this:
>
> > my.fun <- function(x, mult) mult*sum(x)
>
> Now, I want to apply this function along with some other (say
'max') to a
> simple data.frame, like:
>
> > dat <- data.frame(x = 1:4, grp =
c("a","a","b","b"))
>
> Ideally, the result would look something like this (if mult = 10):
>  max my.fun
> a   2     30
> b   4     70
>
> I have tried it that way:
>
> apply.more.functions <- function(dat, FUN = c("max",
"my.fun"), ...) {
>  res <- NULL
>  for(f in FUN) res[[f]] <- tapply(dat$x, dat$grp, FUN = f, ...)
>  data.frame(res)
> }
>
> # let's test it:
> > apply.more.functions(dat, FUN = c("max", "min"))
>  max min
> a   2   1
> b   4   3
> # perfect!
>
> # now, with an additional argument:
> > apply.more.functions(dat, FUN = c("max",
"my.fun"), mult = 10)
>  max my.fun
> a  10     30
> b  10     70
> # uhuh!
> Apparently, 'mult' has been used in the calculation of
'max' as well.
> How can I modify apply.more.functions in order to avoid this?
>
> Your advice would be appreciated;
> Kind regards
> Heinrich.
>
> ______________________________________________
> R-help@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.
>
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