[R] Two Noobie questions

[David Winsemius]

On Jan 6, 2009, at 1:50 PM, AllenL wrote:

>
> 1. I have a list of lm (linear model) objects. Is it possible to  
> select,
> through subscripts, a particular element (say, the intercept) from  
> all the
> models? I've tried something like this:

?coef
if your list of models is ml, then perhaps something like this  
partially tested idea:

lapply(ml, function(x) coef(x)[1] )

This is what I get using that formulation an available logistic model:

 > coef(lr.TC_HDL_BMI)[1]
Intercept
-6.132448


>
>
> List[[1:length(list)]][1]
> All members of the list are similar. My goal is to have a list of the
> intercepts and lists of other estimated parameters. Is it better to  
> convert
> to a matrix? How to do this?
>
> 2. Connected to this, how do I convert from a list back to a vector?  
> This
> problem arose from using "split" to split a vector by a factor, then
> selecting a subset of this (ie. length>10), leaving me with subset  
> list of
> my original. Unsplit(newList, factor) doesn't work, presumably due  
> to my
> removal of some values. Thoughts?

?unlist

 > ll <- list(1,2,3,4)
 > ll
[[1]]
[1] 1

[[2]]
[1] 2

[[3]]
[1] 3

[[4]]
[1] 4

 > unlist(ll)
[1] 1 2 3 4
 > str(unlist(ll))
  num [1:4] 1 2 3 4
 > is.vector(unlist(ll))
[1] TRUE

-- 
David Winsemius
>
>
> Thanks!
> -Allen
>
>
>
> -- 
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