Thanks for this, Bill
Your solution does just what I want. In fact, it qualifies as the
missing as.matrix() method
for n-way tables arranged with ftable(), or vcd::structable(), which
does provide an
as.matrix() method, but omits the names and dimnames.
Here it is, renamed and
using "_" as the default separator for names joined together, which is
probably a better
default. I'll propose this as an addition to the stats package on R-devel.
# modified from Willaim Dunlop, <wdun...@tibco.com>, R-Help, 01-09-2014
as.matrix.ftable <- function(x, sep="_") {
makeDimNames <- function(vars) {
structure(
list(do.call(paste, c(rev(expand.grid(rev(vars))),
list(sep=sep)))),
names = paste(collapse=sep, names(vars))
)
}
structure(
unclass(x),
dimnames=c(makeDimNames(attr(x, "row.vars")),
makeDimNames(attr(x, "col.vars"))),
row.vars=NULL,
col.vars=NULL)
}
Tests:
> UCB <- UCBAdmissions
> as.matrix(ftable(Dept ~ Admit + Gender, data=UCB))
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
> as.matrix(ftable(Dept ~ ., data=UCB))
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
> as.matrix(ftable(Admit + Gender ~ Dept, data=UCB))
Admit_Gender
Dept Admitted_Male Admitted_Female Rejected_Male Rejected_Female
A 512 89 313 19
B 353 17 207 8
C 120 202 205 391
D 138 131 279 244
E 53 94 138 299
F 22 24 351 317
> as.matrix(ftable(Admit ~ ., data=UCB))
Admit
Gender_Dept Admitted Rejected
Male_A 512 313
Male_B 353 207
Male_C 120 205
Male_D 138 279
Male_E 53 138
Male_F 22 351
Female_A 89 19
Female_B 17 8
Female_C 202 391
Female_D 131 244
Female_E 94 299
Female_F 24 317
>
> str(as.matrix(ftable(Admit + Gender ~ Dept, data=UCB)))
num [1:6, 1:4] 512 353 120 138 53 22 89 17 202 131 ...
- attr(*, "dimnames")=List of 2
..$ Dept : chr [1:6] "A" "B" "C" "D" ...
..$ Admit_Gender: chr [1:4] "Admitted_Male" "Admitted_Female"
"Rejected_Male" "Rejected_Female"
>
On 1/9/2014 11:32 AM, William Dunlap wrote:
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-boun...@r-project.org [mailto:r-help-boun...@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
______________________________________________
R-help@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.
--
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
______________________________________________
R-help@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.
