R help - Apr 2005 - functions(t.test) on variables by groups

Dear R users,

I have a data frame with categorical Vars. "Groups"
and a couple  columns of numeric Vars. I am trying to
make two-sample t.test on each variable(s01-s03) by
Groups.

A data generated as following:

zot <- data.frame(Groups=rep(letters[1:2], each=4),
s01=rnorm(8), s02=rnorm(8), s03=rnorm(8))

I have written a piece with a for loop. 
for (i in 1:(length(zot)-1)) {
	print(t.test(zot[,i+1]~zot[,1]))
	            }

I wish something can be easier extracted or can save
it within for loop, or not even using for loop.  

Thanks in advance for your help.

Kevin

Hai Lin <kevinvol2002 at yahoo.com> writes:
> Dear R users,
> 
> I have a data frame with categorical Vars. "Groups"
> and a couple  columns of numeric Vars. I am trying to
> make two-sample t.test on each variable(s01-s03) by
> Groups.
> 
> A data generated as following:
> 
> zot <- data.frame(Groups=rep(letters[1:2], each=4),
> s01=rnorm(8), s02=rnorm(8), s03=rnorm(8))
> 
> I have written a piece with a for loop. 
> for (i in 1:(length(zot)-1)) {
> 	print(t.test(zot[,i+1]~zot[,1]))
> 	            }
> 
> I wish something can be easier extracted or can save
> it within for loop, or not even using for loop.  
Something like this?

lapply(zot[-1],function(x)t.test(x~zot$Groups))


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