[R] aggregate help

[Sam Steingold]

Thanks.
Why does

> aggregate(z, list(id=z$id),FUN=list)
  id         id      a1      a2
1 10 10, 10, 10 a, a, b x, x, z
2 20     20, 20    b, b    y, y
3 30         30       c       z

work, but

aggregate(z, list(id=z$id),FUN=function(l) {
  t <- sort(table(l),decreasing=TRUE)
  list(length(t),t[1],names(t)[1],t[2],names(t)[2])
  })
   id id a1 a2
1 10  1  2  2
2 20  1  1  1
3 30  1  1  1
Warning message:
In format.data.frame(x, digits = digits, na.encode = FALSE) :
  corrupt data frame: columns will be truncated or padded with NAs
  
does not?
(I do not want to put the whole list of all possible values into the
return value of aggregate because I am afraid of running out of ram)

> * arun <fznegcvax111 at lnubb.pbz> [2012-09-20 14:24:37 -0700]:
>
> Hi,
> Try this:
>
> z1<-aggregate(z,list(id=z$id),FUN=paste,sep=",")
> dat1<-data.frame(id=z1[,1],a1.total=unlist(lapply(z1[,3],length)),a1.val1=unique(z$a1),a1.num=unlist(lapply(lapply(z1[,3],table),`[`,1)),a1.val2=unlist(lapply(z1[,3],`[`,3)),a1.num2=unlist(lapply(lapply(z1[,3],table),`[`,2)),a2.total=unlist(lapply(z1[,4],length)),a2.val1=unique(z$a2),a2.num=unlist(lapply(lapply(z1[,4],table),`[`,1)),a2.val2=unlist(lapply(z1[,4],`[`,3)),a2.num2=unlist(lapply(lapply(z1[,4],table),`[`,2)))
> dat1
>
> # id a1.total a1.val1 a1.num a1.val2 a1.num2 a2.total a2.val1 a2.num a2.val2
> #0 10        3       a      2       b       1        3       x      2       z
> #1 20        2       b      2    <NA>      NA        2       y      2    <NA>
> #2 30        1       c      1    <NA>      NA        1       z      1    <NA>
> #  a2.num2
> #0       1
> #1      NA
> #2      NA
> #It is not an elegant way!
>
>
> A.K.
>
>
>
> ----- Original Message -----
> From: Sam Steingold <sds at gnu.org>
> To: r-help at r-project.org
> Cc: 
> Sent: Thursday, September 20, 2012 2:06 PM
> Subject: [R] aggregate help
>
> I want to count attributes of IDs:
> z <- data.frame(id=c(10,20,10,30,10,20),
>                 a1=c("a","b","a","c","b","b"),
>                 a2=c("x","y","x","z","z","y"),
>                 stringsAsFactors=FALSE)
>> z
>   id a1 a2
> 1 10  a  x
> 2 20  b  y
> 3 10  a  x
> 4 30  c  z
> 5 10  b  z
> 6 20  b  y
> I want to get something like
> id a1.tot a1.val1 a1.num1 a1.val2 a1.num2 a2.tot a2.val1 a2.num1 a2.val2 a2.num2
> 10   3     "a"      2      "b"      1       3      "x"     2       "z"     1
> 20   2     "b"      2      <NA>     0       2      "y"     2       <NA>    0
> 30   1     "c"      1      <NA>     0       1      "z"     1       <NA>    0
> (except that I don't care what appears in the cells marked with <NA>)
> I tried this:
> aggregate(z,by=list(id=z$id),function (s) {
>   t <- sort(table(s),decreasing=TRUE)
>   if (length(t) == 1)
>     list(length(s),names(t)[1],t[1],"junk",0)
>   else
>     list(length(s),names(t)[1],t[1],names(t)[2],t[2])
> })
>   id id a1 a2
> 1 10  3  3  3
> 2 20  2  2  2
> 3 30  1  1  1
> Warning message:
> In format.data.frame(x, digits = digits, na.encode = FALSE) :
>   corrupt data frame: columns will be truncated or padded with NAs
> Thanks!

-- 
Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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