I've tried to use by(), but the closest i got to it doing what I wanted
was using the following:
by(percent, quiz, function(percent) {t.test(percent~group,
data=marks.long)})
But the results it gave me weren't t.tests of percent by group according
to quiz number.
Julian Burgos wrote:
> See by()
>
> Matthew Dubins wrote:
>> Hi all,
>>
>> I wrote a simple function that gives me multiple t.test results
>> according to a subset variable and am wondering whether or not I
>> reinvented the wheel. Observe:
>>
>> t.test.sub <- function (formula, data, sub, ...)
>> {
>> for(i in 1:max(sub))
>> {
>> print(t.test(formula, data = subset(data, sub == i),
>> ...))
>> }
>> }
>>
>> Is there already a similar function in some package?
>>
>> Thanks,
>> Matthew Dubins
>>
>> ______________________________________________
>> 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.
>
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