[R] Lists into matrices within lists...again

[Peter Alspach]

Tena koe Edward

It is difficult to know the best approach from the information supplied,
but using unlist() at the appropriate place in your code, maybe
unlist(stats[[i]]$means), will probably get you where you want to be.

HTH .....

Peter Alspach 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of ewaters
> Sent: Tuesday, 23 February 2010 3:27 p.m.
> To: r-help at r-project.org
> Subject: [R] Lists into matrices within lists...again
> 
> 
> Related questions to this have been asked before, but I have 
> tried all options they gave me unsuccessfully (do.call and unlist).
> 
> I start with three lists of summary statistics,  100 elements 
> each, which I bind together:
> 
> statslist <- as.data.frame(cbind (means, vars, mcrs))
> 
> I then take 100 samples of this data frame of varying lengths:
> 
> stats <- lapply (1:100, function (dummy) { 
> statslist[sample(nrow(statslist), (sample (10:20, 1, replace 
> = TRUE)), replace = TRUE),]})
> 
> It returns basically what I want:
> 
> > stats[[i]]
>      means      vars        mcrs
> 71    1.81  3.832222     2.92725
> 9     2.56  8.127677    4.734874
> 91    3.44   9.66303     5.24902
> 68    0.14 0.1216162 0.008686869
> 
> except that:
> 
> > is.list(stats[[i]]$means)
> [1] TRUE
> 
> I don't want this to be a list, because I want to do 
> regressions using the variable which are in columns, which 
> apparently R won't do if they are in lists.
> 
> I have tried every possible combination of working with 
> do.call, rbind, as.data.frame, etc to get this into matrix 
> form to no avail.
> 
> I have also tried using sapply instead of lapply, but that 
> returns vectors which again, R doesn't want to do regression on.
> 
> Any tips would be very much appreciated, been going around in 
> circles for a while here.
> 
> Edward Waters
> PhD Student UNSW
> 
> 
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