Re: [R] extracting columns from a list

From: David Winsemius <dwinsemius_at_comcast.net>
Date: Mon, 26 May 2008 19:30:14 +0000 (UTC)

Vincent Goulet <vincent.goulet_at_act.ulaval.ca> wrote in news:B99F4ABB-08AC-4470-A21C-D719D67C8D74_at_act.ulaval.ca:

> Le ven. 23 mai à 09:37, mohamed nur anisah a écrit :
>

>> Dear all,
>>
>>  i have 2 lists of data with each of the list contain 14 columns.

>
> No, you have one list with two elements; each is a 14-column data
> frame.
>
>> How am i going to extract column 12 and 13 from each of the list ??

>
> Let's call your list 'x'. Then
>
> lapply(x, "[", c(12, 13))
>
> or, better yet,
>
> lapply(x, "[", c("breakp.start", "breakp.end"))
>
> if I counted your columns correctly.
>
>> and can i combine my extracted columns to form a single list.

>
> You mean a single data frame? Given that the number of rows is not
> the same in both elements, no. If they were, using sapply() instead
> of lapply() would do the trick.
>
> HTH Vincent

(Many thanks, Dr Goulet, for your actuarial package.)

I am wondering if he meant to combine his 13 rows and append 22 rows with a result of 35 rows and 2 columns. If so, then perhaps he should see:

?rbind

When I employ rbind to the components of your suggested object:

k0 <- lapply(x, "[", c("breakp.start", "breakp.end"))[[1]]
k1 <- lapply(x, "[", c("breakp.start", "breakp.end"))[[2]]
df2 <- rbind(k0,k1)

I get rather odd rownames (row 14 is named "110" followed by "23, "31", etc) , but this fix "works" for me:

str(df2)
# 'data.frame':

rownames(df2) <- 1:35

> df2

   breakp.start breakp.end

1       6978022    6992734
2      10249966   10277430
3      10955201   11008526
4      11045352   11316865
5      11814604   11937228
6      13847633   14515091
7      16022770   16199850
8      23625856   23754554
9      29676192   29763918
10     30164446   30611872
11     34558312   34734404
12     44009616   44088256
13     53582632   53654796
14      7428353    8356932
15     20225456   20641584
16     33046200   33175188
17     57970280   64939220
18     70011280   70039784
19     70677328   71241272
20     71362456   71425576
21     71824776   73894168
22     74014744   74705408
23     90487648   91228160

24 101058192 101967264
25 102176888 102230040
26 102409592 103123352
27 110591464 116044144
28 116407200 118512328
29 131185424 131616688
30 132395992 132461760
31 137564368 137927776
32 142716752 145888160
33 148377392 148480704
34 148838944 150553856
35 154876816 154971520
-- 
David Winsemius

______________________________________________
R-help_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Received on Mon 26 May 2008 - 19:33:34 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Mon 26 May 2008 - 20:31:29 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive