# [R] Tabulating using arbitrary numbers of factors

Jim Lemon jim at bitwrit.com.au
Sun Oct 4 06:50:15 CEST 2009

```On 10/03/2009 04:15 AM, Andrew Spence wrote:
> Dear R-help,
>
>
>
> First of all, thank you VERY much for any help you have time to offer. I
> greatly appreciate it.
>
>
>
> I would like to write a function that, given an arbitrary number of factors
> from a data frame, tabulates the number of occurrences of each unique
> combination of the factors. Cleary, this works:
>
>
>
>
>> table(horse,date,surface)
>>
> <SNIP>
>
> , , surface = TURF
>
>
>
>                     date
>
> horse               20080404 20080514 20081015 20081025 20081120 20081203
> 20090319
>
>    Bedevil                  0        0        0        0        0        0
> 0
>
>    Cut To The Point       227        0        0        0        0        0
> 0
>
> <SNIP>
>
>
>
> But I would prefer output that skips all the zeros, flattens any dimensions
> greater than 2, and gives the level names rather than codes. I can write
> code specifically for n factors like this: (here 2 levels):
>
>
>
> ft<- function(x,y) {cbind(
> levels(x)[unique(cbind(x,y))[,1]],levels(y)[unique(cbind(x,y))[,2]],
> table(x,y)[unique(cbind(x,y))])}
>
>
>
> which gives the lovely output I'm looking for:
>
>
>
> #      [,1]                [,2]       [,3]
>
> # [1,] "Cut To The Point"  "20080404" "227"
>
> # [2,] "Prairie Wolf"      "20080404" "364"
>
> # [3,] "Bedevil"           "20080514" "319"
>
> # [4,] "Prairie Wolf"      "20080514" "330"
>
>
>
> But my attempts to make this into a function that handles arbitrary numbers
> of factors as separate input arguments has failed. The closest I can get is:
>
>
>
> ft2<- function (...) { cbind( unique(cbind(...)),
> table(...)[unique(cbind(...))] )
>
>
>
> giving:
>
>
>> ft2(horse,date)
>>
>        horse date
>
>   [1,]     2    1 227
>
>   [2,]     9    1 364
>
>   [3,]     1    2 319
>
>   [4,]     9    2 330
>
>   [5,]     9    3 291
>
>   [6,]    12    3 249
>
>   [7,]    10    3 286
>
>   [8,]     5    4 217
>
>   [9,]     3    4 426
>
> [10,]     8    4 468
>
> [11,]     9    5 319
>
> [12,]    13    5 328
>
> [13,]    12    5 138
>
> [14,]     7    6 375
>
> [15,]    11    6 366
>
> [16,]     4    7 255
>
> [17,]     6    7 517
>
>
>
> I would be greatly in debt to anyone willing to show me how to make the
> above function take arbitrary inputs and still produce output displaying
> factor level names instead of the underlying coded numbers.
>
>
Hi Andrew,
The sizetree function in plotrix does what you want graphically, I
think. Perhaps if each invocation returned the vector of counts, the
deepest level of counts would be returned at the final exit with the
factor levels.

Jim

```