That's a dandy little program but the apply with lapply blew my mind! I had to
pick it apart to figure out what it was doing. Perhaps others will find this
expanded version useful:
# Make up some repeated measures data with measures at 4 times.
t1<-c(1,2,3,4,5)
t2<-c(2,3,3,5,5)
t3<-c(3,3,4,4,4)
t4<-c(5,6,6,7,7)
myTimes<-data.frame(t1,t2,t3,t4)
myTimes
# Get matrix of combinations of 4 things taken two at a time.
myCombos<-combn( ncol(myQs), 2 )
myCombos
# Generate a list that contains all the pairs of times.
myTimesList <- apply( myCombos, 2, function(y) myTimes[ ,y] )
myTimesList
# apply the t.test function to each set of pairs in the myTimeCombos
lapply( myTimesList,
function(z) t.test( z[ ,1], z[ ,2] )
)
Cheers,
Bob
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> project.org] On Behalf Of Henrique Dallazuanna
> Sent: Tuesday, January 29, 2008 9:15 AM
> To: nalluri pratap
> Cc: r-help@r-project.org
> Subject: Re: [R] Form Pairs of Variables for a paired t-test
>
> Try this:
>
> lapply(apply(combn(ncol(x),2), 2, function(y)x[,y]),
> function(z)t.test(z[,1], z[,2]))
>
> On 29/01/2008, nalluri pratap <[EMAIL PROTECTED]> wrote:
> > Hi Users,
> >
> > This is regarding the paired t-test. I have 5 variables (say)
> Data$v1,Data$v2,Data$v3,Data$v4,Data$v5 in my data frame. Now, I need
> to perform a paired t-test on all the possible 10 pairs.How do I set up
> the pairs table directly and pass those variables in to t-test.
> >
> > Thanks in advance,
> >
> > Pratap
> >
> >
> > ---------------------------------
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> >
>
>
> --
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>
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> and provide commented, minimal, self-contained, reproducible code.
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