[R] Have a function like the "_n_" in R ? (Automatic count function )

[hadley wickham]

And for completeness here's a function that returns the next integer
on each call.

n <- (function(){
  i <- 0
  function() {
    i <<- i + 1
    i
  }
})()

> n()
[1] 1
> n()
[1] 2
> n()
[1] 3
> n()
[1] 4
> n()
[1] 5
> n()
[1] 6


;)

Hadley

On Wed, Feb 25, 2009 at 8:27 AM, David Winsemius <dwinsemius at comcast.net> wrote:
> The _n_ construct in SAS is most analogous to that of row names in R,
> accessible (and modifiable)  via the row.names() function:
>
> DF <- structure(list(Month = structure(c(2L, 2L, 2L, 2L, 1L, 1L, 1L,
> 1L, 3L, 3L, 3L, 3L, 3L), .Label = c("Aug", "July", "Sept"), class =
> "factor"),
>    Week = 27:39, Estpassage = c(665L, 2232L, 9241L, 28464L,
>    41049L, 82216L, 230411L, 358541L, 747839L, 459682L, 609567L,
>    979475L, 837189L), MedFL = c(34L, 35L, 35L, 35L, 35L, 35L,
>    35L, 35L, 35L, 36L, 36L, 36L, 36L)), .Names = c("Month",
> "Week", "Estpassage", "MedFL"), class = "data.frame", row.names = c(NA,
> -13L))
>
> DF$counter <- row.names(DF)
>
>> DF
>   Month Week Estpassage MedFL counter
> 1   July   27        665    34       1
> 2   July   28       2232    35       2
> 3   July   29       9241    35       3
> 4   July   30      28464    35       4
> 5    Aug   31      41049    35       5
> 6    Aug   32      82216    35       6
> 7    Aug   33     230411    35       7
> 8    Aug   34     358541    35       8
> 9   Sept   35     747839    35       9
> 10  Sept   36     459682    36      10
> 11  Sept   37     609567    36      11
> 12  Sept   38     979475    36      12
> 13  Sept   39     837189    36      13
>
> Row names, however, not guaranteed to be integer, although if not specified
> at time of creation a dataframe will have its row names set to an ascending
> series of integer type. Another function that would provide similar utility
> for vectors might be seq_along().\, but in the case of dataframes, it may
> confuse the beginning R user because it will return a column oriented
> ascending sequence.
>
>> seq_along(DF)
> [1] 1 2 3 4 5
>
> --
> David Winsemius
>
>
>
> On Feb 25, 2009, at 7:25 AM, Nash wrote:
>
>>
>> Have the counter function in R ?
>>
>> if we use the software SAS
>>
>> /*** SAS Code **************************/
>> data tmp(drop= i);
>> retain seed x 0;
>> do i = 1 to 5;
>>        call ranuni(seed,x);
>>        output;
>> end;
>> run;
>>
>> data new;
>> counter=_n_;  ***** this keyword _n_ ****;
>> set tmp;
>> run;
>>
>> /*
>> _n_ (Automatic variables)
>> are created automatically by the DATA step or by DATA step statements.
>> */
>>
>> /*** Output ********************************
>> counter      seed             x
>> 1       584043288                0.27197
>> 2       935902963                0.43581
>> 3       301879523                0.14057
>> 4       753212598                0.35074
>> 5       1607264573      0.74844
>>
>> ********************************************/
>>
>> Have a function like the "_n_" in R ?
>>
>>
>> --
>> Nash - morrison at ibms.sinica.edu.tw
>>
>> ______________________________________________
>> 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.
>
> ______________________________________________
> 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.
>



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