[Rd] ftable.formula
William Dunlap
wdunlap at tibco.com
Fri Jan 27 02:06:39 CET 2012
Put the formula first in the argument list or label
the data argument data= and put the formula after it
if you want to use the formula method for ftable.
> ftable(data=UCBAdmissions, Gender + Admit ~ Dept)
Gender Male Female
Admit Admitted Rejected Admitted Rejected
Dept
A 512 313 89 19
B 353 207 17 8
C 120 205 202 391
D 138 279 131 244
E 53 138 94 299
F 22 351 24 317
The array method for ftable appears to ignore a formula.
It expects a row.vars and/or col.vars argument:
> ftable(UCBAdmissions, nonSense ~ more + nonSense)
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
Since most generic functions and methods have ... in the
argument list you don't get warned about supplying
arguments that the method does not expect.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at r-project.org] On Behalf Of Timothy Bates
> Sent: Thursday, January 26, 2012 3:17 PM
> To: r-devel at stat.math.ethz.ch
> Subject: Re: [Rd] ftable.formula
>
> At least this is correct :-)
>
> ftable(UCBAdmissions, Dept ~ Gender + Admit)
>
> But yes: the formula
> ftable(UCBAdmissions, Gender + Admit ~ Dept)
>
> should see "The left and right hand side of formula specify the column and row variables,
> respectively"
>
> # demo of right-hand side bug
>
> ftable(UCBAdmissions, Gender + Admit ~ Dept) # "Dept" should be in the rows...
> 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
>
>
> Also, the example appears not to be a correct use of the "." shortcut.
>
> x <- ftable(Survived ~ ., data = Titanic)
> # Error in ftable.formula(Survived ~ ., data = Titanic) :
> # cannot use dots in formula with given data
>
> Also "Survived" should be "survived"
> And in this example, all vars should be lower-case
>
> ftable(Sex ~ Class + Age, data = x)
>
> t
>
> On 26 Jan 2012, at 22:31, Brett Presnell wrote:
> > From reading the documentation for ftable.formula, I expected that the
> > following two calls to ftable would produce the same results:
> >
> > data(UCBAdmissions)
> > ftable(UCBAdmissions, row.vars = "Dept", col.vars = c("Gender", "Admit"))
> > ftable(UCBAdmissions, Gender + Admit ~ Dept)
> >
> > Is this a bug or the intended behavior? I prefer the formula interface,
> > so I would be happiest if the output was the same for the two calls.
> > However, if this is the intended behavior, then I think that the
> > documentation should be clearer on this point.
>
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