[R] Multiple t.test

[Uwe Ligges]

On 12.09.2011 13:16, Raphael Saldanha wrote:
> Hi!
>
> Try something like this:
>
> subset(example, disease==TRUE)
> subset(example, disease==FALSE)


Hmmm, I think the actual answer to the question is something along this 
line:

sapply(example[names(example)!="disease"],
        function(x) t.test(x ~ example[["disease"]])[[3]])


Uwe Ligges



>
> On Mon, Sep 12, 2011 at 4:54 AM, C.H.<chainsawtiney at gmail.com>  wrote:
>
>> Dear R experts,
>>
>> Suppose I have an data frame likes this:
>>
>>> example<- data.frame(age=c(1,2,3, 4,5,6),
>> height=c(100,110,120,130,140,150), disease=c(TRUE, TRUE, TRUE, FALSE, FALSE,
>> FALSE))
>>
>>> example
>>   age height disease
>> 1   1    100    TRUE
>> 2   2    110    TRUE
>> 3   3    120    TRUE
>> 4   4    130   FALSE
>> 5   5    140   FALSE
>> 6   6    150   FALSE
>>
>> Is there anyway to compare the age and height between those with
>> disease=TRUE and disease=FALSE using t.test and extract the p-values
>> quickly?
>>
>> I can do this individually
>>
>> t.test(example$age~example$disease)[3]
>>
>> But when the number of variable grow to something like 200 it is not
>> easy any more.
>>
>> Thanks!
>>
>> Regards,
>>
>> CH
>>
>> --
>> CH Chan
>>
>> ______________________________________________
>> R-help at 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.
>>
>
>
>