[R] take two columns from a set of lists

arun smartpink111 at yahoo.com
Mon Mar 11 13:46:40 CET 2013


You could also do:
simplify2array(x.list)[2,]
#[1] 0.1 3.0
A.K.



----- Original Message -----
From: Jorge I Velez <jorgeivanvelez at gmail.com>
To: ishi soichi <soichi777 at gmail.com>
Cc: r-help <r-help at r-project.org>
Sent: Monday, March 11, 2013 6:57 AM
Subject: Re: [R] take two columns from a set of lists

Is the following that you are looking for?

unlist(lapply(x.list, "[", 2))

HTH,
Jorge.-


On Mon, Mar 11, 2013 at 9:52 PM, ishi soichi <> wrote:

> say I have a matrix and lists like
>
> x <- matrix(c(12.1, 3.44, 0.1, 3, 12, 33.1, 1.1, 23), nrow=2)
>
> x.list <- lapply(seq_len(nrow(x)), function(i) x[i,])
>
> if I want a column of the matrix x, I write
>
> x[, 2]
>
> for example.
>
> But how can I do something similar for a set of lists, x.list, above?
>
> > x.list
> [[1]]
> [1] 12.1  0.1 12.0  1.1
>
> [[2]]
> [1]  3.44  3.00 33.10 23.00
>
> unlist(x.list)[,2] does not work.
>
>
> Anyone?
>
> ishida
>
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>
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