[R] aggregate function

[jim holtman]

You were using the wrong syntax; it should be:

 x[
     , list(case1 = paste(case1, collapse = ','))
     , by = param
   ]

Notice that you do not use the "x$" on the names within the data.table
statement.

On Wed, Dec 21, 2011 at 12:22 PM, Mary Kindall <mary.kindall at gmail.com> wrote:
> Hi Jim
>
> Thanks for reply but this is not working. I think I am missing something
> over here.
>
> 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
>>>> PLEASE do read the posting guide
>>>> 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
>>> PLEASE do read the posting guide
>>> 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
>



-- 
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.