[R] aggregate function

[peter dalgaard]

On Dec 21, 2011, at 18:22 , Mary Kindall wrote:

> Hi Jim
> 
> Thanks for reply but this is not working. I think I am missing something
> over here.

Yes, the data.table() bit. It's not going to work with data frames.

> 
> 1> x <- cbind(c(1,2,2,2,3,4), c('a','b', 'c','d','e','f'))
> 1> colnames(x) = c('param', 'case1')
> 1> x = as.data.frame(x)
> 1> x
>  param case1
> 1     1     a
> 2     2     b
> 3     2     c
> 4     2     d
> 5     3     e
> 6     4     f
> 1> x[
> 1+      , list(case1 = paste(x$case1, collapse = ','))
> 1+      , by = x$param
> 1+   ]
> Error in `[.data.frame`(x, , list(case1 = paste(x$case1, collapse = ",")),
> :
>  unused argument(s) (by = x$param)
> 
> 
> Hi David.
> Thanks a lot for your help.
> 
> 1> aggregate(x$case1, x['param'], FUN = paste, collapse=",")
>  param     x
> 1     1     a
> 2     2 b,c,d
> 3     3     e
> 4     4     f
> 1>
> 
> 
> Thanks again
> M
> 
> 
> On Wed, Dec 21, 2011 at 11:56 AM, David Winsemius <dwinsemius at comcast.net>wrote:
> 
>> 
>> On Dec 21, 2011, at 11:31 AM, jim holtman wrote:
>> 
>> Here is an example using 'data.table'"
>>> 
>>> x <- read.table(text = "param       case1
>>>> 
>>> + 1               a
>>> + 2               b
>>> + 2               c
>>> + 2               d
>>> + 3               e
>>> + 4               f", header = TRUE, as.is = TRUE)
>>> 
>> 
>> And the aggregate version:
>> 
>>> aggregate(x$case1, x["param"], FUN=paste, collapse=",")
>> param     x
>> 1     1     a
>> 2     2 b,c,d
>> 3     3     e
>> 4     4     f
>> 
>> ( Generally one uses the "[[" function for extraction, but using  "["
>> returns a list which is what aggregate is designed to process as its second
>> argument, whereas you would get an error with either of these:
>> 
>> aggregate(x$case1, x$param, FUN=paste, collapse=",")
>> aggregate(x$case1, x[["param"]], FUN=paste, collapse=",")
>> 
>> )
>> 
>> require(data.table)
>>>> x <- data.table(x)
>>>> x[
>>>> 
>>> +     , list( case1 = paste(case1, collapse = ','))
>>> +     , by = param
>>> +  ]
>>>   param case1
>>> [1,]     1     a
>>> [2,]     2 b,c,d
>>> [3,]     3     e
>>> [4,]     4     f
>>> 
>>>> 
>>>> 
>>> 
>>> On Wed, Dec 21, 2011 at 11:26 AM, Mary Kindall <mary.kindall at gmail.com>
>>> wrote:
>>> 
>>>> Hi
>>>> I have a data frame with values in following format.
>>>> 
>>>> 
>>>> param       case1
>>>> 1               a
>>>> 2               b
>>>> 2               c
>>>> 2               d
>>>> 3               e
>>>> 4               f
>>>> 
>>>> 
>>>> how to use aggregate so that it I only one row for each 'param' value.
>>>> 
>>>> the output for the above input should be
>>>> 
>>>> param     case1
>>>> 1      a
>>>> 2      b,c,d
>>>> 3      e
>>>> 4      f
>>>> 
>>>> Thanks
>>>> M
>>>> 
>>>> 
>>>> 
>>>> --
>>>> -------------
>>>> Mary Kindall
>>>> Yorktown Heights, NY
>>>> USA
>>>> 
>>>>      [[alternative HTML version deleted]]
>>>> 
>>>> ______________________________**________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>>>> PLEASE do read the posting guide http://www.R-project.org/**
>>>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> Jim Holtman
>>> Data Munger Guru
>>> 
>>> What is the problem that you are trying to solve?
>>> Tell me what you want to do, not how you want to do it.
>>> 
>>> ______________________________**________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>>> PLEASE do read the posting guide http://www.R-project.org/**
>>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>>> and provide commented, minimal, self-contained, reproducible code.
>>> 
>> 
>> David Winsemius, MD
>> West Hartford, CT
>> 
>> 
> 
> 
> -- 
> -------------
> Mary Kindall
> Yorktown Heights, NY
> USA
> 
> 	[[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.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com