Re: [R] summing values according to a factor

From: Salvatore Enrico Indiogine <>
Date: Mon, 07 May 2007 14:59:06 -0500

Dear Andy and all others who have replied:

On 07/05/07, Liaw, Andy <> wrote:
> I guess what you want to do is compare Q1/T1 among the sections? If you
> want to compute the sum of Q1/T1 by Section, you can do something like:
> <- with(mydata, tapply(Q1/T1, section, sum))
> Substitute sum with anything you want to compute.

That worked perfectly. Thanks!


Enrico Indiogine

Mathematics Education
Texas A&M University

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Received on Mon 07 May 2007 - 20:03:51 GMT

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