R help - Sep 2015 - by Function Result Factor Levels

Good day,

How is it possible to get a data.frame of factor levels used for obtaining each
element of the result of the by function ? For example,

result <- by(warpbreaks[, 1],   warpbreaks[, -1],
summary)
> result
wool: A
tension: L
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
  25.00   26.00   51.00   44.56   54.00   70.00 
 ...

I'd like to obtain a data.frame of the two columns, wool and tension,
specifying the level of each factor that corresponds to each element of result.

--------------------------------------
Dario Strbenac
PhD Student
University of Sydney
Camperdown NSW 2050
Australia

Do you want something like the following?
> library(dplyr, quietly=TRUE, warn.conflicts=FALSE)
> warpbreaks %>% group_by(wool, tension) %>% summarize(Min=min(breaks),
Median=median(breaks), Max=max(breaks))
Source: local data frame [6 x 5]
Groups: wool

  wool tension Min Median Max
1    A       L  25     51  70
2    A       M  12     21  36
3    A       H  10     24  43
4    B       L  14     29  44
5    B       M  16     28  42
6    B       H  13     17  28

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Tue, Sep 15, 2015 at 7:00 PM, Dario Strbenac
<dstr7320 at uni.sydney.edu.au> wrote:
> Good day,
>
> How is it possible to get a data.frame of factor levels used for obtaining
each element of the result of the by function ? For example,
>
> result <- by(warpbreaks[, 1],   warpbreaks[, -1], summary)
>> result
> wool: A
> tension: L
>    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
>   25.00   26.00   51.00   44.56   54.00   70.00
>  ...
>
> I'd like to obtain a data.frame of the two columns, wool and tension,
specifying the level of each factor that corresponds to each element of result.
>
> --------------------------------------
> Dario Strbenac
> PhD Student
> University of Sydney
> Camperdown NSW 2050
> Australia
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Good day,

Yes, exactly. I found that aggregate is another alternative which doesn't
require a package dependency, although the column formatting is less suitable,
always prepending x.

aggregate(warpbreaks[, 1], warpbreaks[, 2:3], function(breaks) c(Min =
min(breaks), Med = median(breaks), Max = max(breaks)))
  wool tension x.Min x.Med x.Max
1    A       L    25    51    70
2    B       L    14    29    44
3    A       M    12    21    36
4    B       M    16    28    42
5    A       H    10    24    43
6    B       H    13    17    28

--------------------------------------
Dario Strbenac
PhD Student
University of Sydney
Camperdown NSW 2050
Australia