take two columns from a set of lists

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.-

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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