Re: [R] Dividing a vector into ntiles

From: Ravi Varadhan <rvaradha_at_jhsph.edu>
Date: Fri 15 Jul 2005 - 23:49:46 EST


Here is an example that shows how to divide a vector into "quartiles" and create a categorical (factor) variable with 4 levels ("A", "B", "C", "D") from it:

x <- rnorm(100)
xcat <- factor(cut(x, quantile(x), include.lowest = TRUE),

                  labels = LETTERS[1:4])
table(xcat)

Ravi.

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch [mailto:r-help-
> bounces@stat.math.ethz.ch] On Behalf Of John Sorkin
> Sent: Friday, July 15, 2005 8:48 AM
> To: r-help@stat.math.ethz.ch
> Subject: [R] Dividing a vector into ntiles
>
> R 2.1.1
> Win 2k
>
> Would someone suggest a method (or methods) that can be used to
> determine ntile cutpoints of a vector, i.e. to determine values that can
> be used to divide a vector into thirds such as 0-33 centile, 34-66
> centile, 67-100 centile. If for example I had a vector:
> 1,2,3,4,5,6,7,8,9
> and wanted to divide the vector into thirds
> I would have cut-points of 3, and 6.
> Thanks,
> John
>
> John Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> Baltimore VA Medical Center GRECC and
> University of Maryland School of Medicine Claude Pepper OAIC
>
> University of Maryland School of Medicine
> Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
>
> 410-605-7119
> -- NOTE NEW EMAIL ADDRESS:
> jsorkin@grecc.umaryland.edu
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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



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 Received on Fri Jul 15 23:52:54 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:33:45 EST