[R] Dividing a vector into ntiles

[Ravi Varadhan]

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 at stat.math.ethz.ch [mailto:r-help-
> bounces at stat.math.ethz.ch] On Behalf Of John Sorkin
> Sent: Friday, July 15, 2005 8:48 AM
> To: r-help at 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:
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> 
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