[R] recoding table dimensions interactively
William Dunlap
wdunlap at tibco.com
Thu Jan 9 17:32:47 CET 2014
Do you just want to change how the rows and columns of ftable's output are
labelled? If so, the following may do what you want: it produces a matrix
with dimnames based on the row.vars and col.vars attributes of ftable's
output.
f <- function(ftable) {
makeDimNamesEl <- function(x) {
structure(
list(do.call(paste, c(rev(expand.grid(rev(x))), list(sep=":")))),
names = paste(collapse=":", names(x))
)
}
structure(
unclass(ftable),
dimnames=c(makeDimNamesEl(attr(ftable, "row.vars")),
makeDimNamesEl(attr(ftable, "col.vars"))),
row.vars=NULL,
col.vars=NULL)
}
E.g.,
> f(ftable(UCBAdmissions))
Dept
Admit:Gender A B C D E F
Admitted:Male 512 353 120 138 53 22
Admitted:Female 89 17 202 131 94 24
Rejected:Male 313 207 205 279 138 351
Rejected:Female 19 8 391 244 299 317
> f(ftable(data=mtcars, am + gear ~ vs + carb))
am:gear
vs:carb 0:3 0:4 0:5 1:3 1:4 1:5
0:1 0 0 0 0 0 0
0:2 4 0 0 0 0 1
0:3 3 0 0 0 0 0
0:4 5 0 0 0 2 1
0:6 0 0 0 0 0 1
0:8 0 0 0 0 0 1
1:1 3 0 0 0 4 0
1:2 0 2 0 0 2 1
1:3 0 0 0 0 0 0
1:4 0 2 0 0 0 0
1:6 0 0 0 0 0 0
1:8 0 0 0 0 0 0
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Michael Friendly
> Sent: Thursday, January 09, 2014 7:14 AM
> To: R-help
> Subject: [R] recoding table dimensions interactively
>
> Given a 3+ way table, I'd like a simple, elegant way to flatten the
> table to a two-way
> table, with some variables joined interactively to form the rows and
> others forming
> the columns. For example, starting with
>
> > str(UCBAdmissions)
> table [1:2, 1:2, 1:6] 512 313 89 19 353 207 17 8 120 205 ...
> - attr(*, "dimnames")=List of 3
> ..$ Admit : chr [1:2] "Admitted" "Rejected"
> ..$ Gender: chr [1:2] "Male" "Female"
> ..$ Dept : chr [1:6] "A" "B" "C" "D" ...
> >
>
> What I want is something similar to the result of ftable:
>
> > ftable(UCBAdmissions)
> Dept A B C D E F
> Admit Gender
> Admitted Male 512 353 120 138 53 22
> Female 89 17 202 131 94 24
> Rejected Male 313 207 205 279 138 351
> Female 19 8 391 244 299 317
>
> One way to do this is to convert to a data.frame, paste the factors
> together and then convert back to a table:
>
> UCB.df <- as.data.frame(UCBAdmissions)
> UCB.df$`Admit:Gender` <- paste(UCB.df$Admit, UCB.df$Gender, sep=':')
> UCB.tab2 <- xtabs(Freq ~ `Admit:Gender` + Dept, data=UCB.df)
> UCB.tab2
>
> > UCB.tab2
> Dept
> Admit:Gender A B C D E F
> Admitted:Female 89 17 202 131 94 24
> Admitted:Male 512 353 120 138 53 22
> Rejected:Female 19 8 391 244 299 317
> Rejected:Male 313 207 205 279 138 351
> >
>
> But maybe there is a simpler, more elegant and general way to do this.
>
> --
> Michael Friendly Email: friendly AT yorku DOT ca
> Professor, Psychology Dept. & Chair, Quantitative Methods
> York University Voice: 416 736-2100 x66249 Fax: 416 736-5814
> 4700 Keele Street Web:http://www.datavis.ca
> Toronto, ONT M3J 1P3 CANADA
>
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