From: George W. Gilchrist <gwgilc_at_wm.edu>

Date: Sat 23 Sep 2006 - 12:44:44 GMT

* > t.ind <- NULL
*

* > for (i in 1:3) t.ind <- c(t.ind, seq(tmp1[i,1], tmp1[i,2]))
*

* > t.ind
*

[1] 2 3 4 5 7 8 9 15 16 17 18 19 20

* >
*

Williamsburg, VA 23187-8795

http://gwgilc.people.wm.edu/

R-help@stat.math.ethz.ch 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 Sat Sep 23 22:49:42 2006

Date: Sat 23 Sep 2006 - 12:44:44 GMT

I have a very large dataframe and wish to extract a subset of rows. I
have a two column matrix listing the starting and ending indices of
one subset on each row. My idea is to create a vector of indices that
could be applied to the dataframe and I have a solution using a for
loop (below). But surely there is some more elegant way to do this! I
looked thorough the archives without success. Thanks for any ideas.

* > tmp1 <- matrix(c(2,5,7,9,15,20), 3,2, byrow=T)
** > tmp1
*

[1,] 2 5 [2,] 7 9 [3,] 15 20

[1] 2 3 4 5 7 8 9 15 16 17 18 19 20

cheers, George

.................................................................. George W. Gilchrist Email: gwgilc@wm.edu Director of Graduate Studies Phone: (757) 221-7751 Department of Biology, Box 8795 Fax: (757) 221-6483College of William & Mary

Williamsburg, VA 23187-8795

http://gwgilc.people.wm.edu/

R-help@stat.math.ethz.ch 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 Sat Sep 23 22:49:42 2006

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