# Re: [R] help on retrieving output from by( ) for regression

From: Randy Johnson <rjohnson_at_ncifcrf.gov>
Date: Fri 26 Aug 2005 - 02:17:18 EST

Randy

On 8/25/05 9:44 AM, "Marc Schwartz" <MSchwartz@mn.rr.com> wrote:

> Also, looking at the last example in ?by would be helpful:
>
> attach(warpbreaks)
> tmp <- by(warpbreaks, tension, function(x) lm(breaks ~ wool, data = x))
>
> # To get coefficients:
> sapply(tmp, coef)
>
> # To get residuals:
> sapply(tmp, resid)
>
> # To get the model matrix:
> sapply(tmp, model.matrix)
>
>
>
> To get the summary() output, I suspect that using:
>
> lapply(tmp, summary)
>
> would yield more familiar output as compared to using:
>
> sapply(tmp, summary)
>
> The output from the latter might require a bit more "navigation" through
> the resultant matrix, depending upon how the output is to be ultimately
> used.
>
> HTH,
>
> Marc Schwartz
>
>
>
> On Thu, 2005-08-25 at 14:57 +0200, TEMPL Matthias wrote:

```>> Look more carefully at
>> ?lm
>>
>> X <- rnorm(30)
>> Y <- rnorm(30)
>> lm(Y~X)
>> summary(lm(Y~X))
>>
>> Best,
>> Matthias
>>
>>
>>> Hi all
>>>
>>> I used a function
>>>> qtrregr <- by(AB, AB\$qtr, function(AB) lm(AB\$X~AB\$Y))
>>>
>>> objective is to run a regression on quartery subsets in the
>>> data set AB, having variables X and Y, grouped by variable qtr.
>>>
>>> Now i retrieved the output using qtrregr, however it only
>>> showed the coefficients (intercept and B) with out
>>> significant levels and residuals for each qtr. Can some on
>>> help me on how can retrieve the detailed regression output.
>>>
>>> rgds
>>>
>>> snvk
>>>
```

>
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Randy Johnson
Laboratory of Genomic Diversity
NCI-Frederick
Bldg 560, Rm 11-85
Frederick, MD 21702
(301)846-1304

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