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:

jsorkin at grecc.umaryland.edu

[[alternative HTML version deleted]]

______________________________________________

R-help at 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

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:

jsorkin at grecc.umaryland.edu

[[alternative HTML version deleted]]

______________________________________________

R-help at 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