[R] Converting a list to a matrix - I still don't think I have itright

[Ravi Varadhan]

This should do it:

matrix(unlist(mylist),nrow=length(mylist), by=T)


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Ravi Varadhan, Ph.D.
Assistant Professor,  The Center on Aging and Health
Division of Geriatric Medicine and Gerontology
Johns Hopkins University
Ph: (410) 502-2619
Fax: (410) 614-9625
Email:  rvaradhan at jhmi.edu
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> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-
> bounces at stat.math.ethz.ch] On Behalf Of michael watson (IAH-C)
> Sent: Thursday, February 17, 2005 9:37 AM
> To: r-help at r-project.org
> Subject: [R] Converting a list to a matrix - I still don't think I have
> itright
> 
> Hi
> 
> We have touched on this before, but I don't think I quite got it right.
> 
> So I have a list, each element of which is a a vector of 2 numbers:
> 
> > l2
> $cat000_a01
> [1] 0.3429944 4.5138244
> 
> $cat000_a02
> [1] 0.1929336 4.3064944
> 
> $cat000_a03
> [1] -0.2607796  4.1551591
> 
> What I actually want to convert this into is a matrix with the names
> (cat000_a01 etc) as row names, the first element of each of the vectors
> forming the first column of the new matrix, and the second element of
> each of the vectors forming the second column:
> 
> cat000_a01	0.3429944	4.5138244
> cat000_a02	0.1929336	4.3064944
> cat000_a03	-0.2607796  4.1551591
> 
> What was suggested on the list last time was
> matrix(unlist(mylist),nrow=length(mylist)).  But if I do this I get:
> 
> > matrix(unlist(l2),nrow=length(l2))
>           [,1]       [,2]
> [1,] 0.3429944  4.3064944
> [2,] 4.5138244 -0.2607796
> [3,] 0.1929336  4.1551591
> 
> Which is not what I want.  Here, the second element of the first vector
> in my list has gone into the first column of the new matrix, and that's
> not what I want at all.
> 
> Any more help would be appreciated.
> 
> Thanks
> Mick
> 
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