From: Dimitris Rizopoulos <Dimitris.Rizopoulos_at_med.kuleuven.be>

Date: Mon, 24 Mar 2008 19:10:36 +0100

Dimitris Rizopoulos

Biostatistical Centre

School of Public Health

Catholic University of Leuven

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 24 Mar 2008 - 18:17:41 GMT

Date: Mon, 24 Mar 2008 19:10:36 +0100

try this:

y <- as.matrix(read.table(textConnection(

"A C G T T G C A G C A C G F F F F F F G A C G S S S S S G A A C G T T G C A G G A B B B B B B A G T"), stringsAsFactors = FALSE))

ind <- sample(length(y), 20, TRUE)

y[ind]

I hope it helps.

Best,

Dimitris

ps, it would be best that you send that kind of e-mails in R-help not R-devel; check http://www.r-project.org/mail.html for more info regarding the different R-mailing-lists.

Dimitris Rizopoulos

Biostatistical Centre

School of Public Health

Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium

Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm

Quoting Suraaga Kulkarni <suraaga.kulkarni_at_gmail.com>:

*> Hi,
**>
**> I need to resample from a long string, which is written in many lines with
**> carriage-return marks at the end of each line. Perhaps because the data
**> looks like a matrix, using the code: sample(data, 25, replace=T) gives me 25
**> columns of characters from the data because it is resampling whole columns.
**> What I would like it to do is to treat the data as a vector that has just
**> been spread across many lines, and pick single characters from random
**> positions in randomly chosen lines.
**>
**> I am reproducing a sample dataset, the command and the output here:
**>
**>> y
**> X..1. X..2. X..3. X..4. X..5. X..6. X..7. X..8. X..9. X..10.
**> [1,] A C G T T G C A G C
**> [2,] A C G F F F F F F G
**> [3,] A C G S S S S S G A
**> [4,] A C G T T G C A G G
*

> [5,] A B B B B B B A G T

*>
**>> sample(y, 20, replace=T)
**> X..9. X..4. X..2. X..7. X..9..1 X..3. X..3..1 X..9..2 X..9..3 X..4..1
**> X..3..2 X..8. X..9..4 X..3..3 X..6. X..7..1
**> [1,] G T C C G G G G G
**> T G A G G G C
**> [2,] F F C F F G G F F
**> F G F F G F F
**> [3,] G S C S G G G G G
**> S G S G G S S
**> [4,] G T C C G G G G G
**> T G A G G G C
**> [5,] G B B B G B B G G
**> B B A G B B B
**>
**> X..6..1 X..3..4 X..7..2 X..10.
**> [1,] G G C C
**> [2,] F G F G
**> [3,] S G S A
**> [4,] G G C G
**> [5,] B B B T
**>
**> I wanted to try the bootstrap approach (since that's what I am doing -
**> resampling with replacement) but that requires a "statistic" and I don't
**> know what sense that makes for character data.
**>
**> Any help will be greatly appreciated.
**>
**> Thanks,
**>
**> S.
**>
**> [[alternative HTML version deleted]]
**>
**> ______________________________________________
**> R-devel_at_r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-devel
**>
**>
*

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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 24 Mar 2008 - 18:17:41 GMT

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