You could try using "cut": > cut(1:9, breaks = 3) [1] (0.992,3.66] (0.992,3.66] (0.992,3.66] (3.66,6.34] (3.66,6.34] [6] (3.66,6.34] (6.34,9.01] (6.34,9.01] (6.34,9.01] Levels: (0.992,3.66] (3.66,6.34] (6.34,9.01] >
Quantile is another possible solution to get break points: > quantile(1:9, p = c(0, .33, .66, 1)) 0% 33% 66% 100% 1.00 3.64 6.28 9.00 > You could use rounding if you want the integers, or use the given cutpoints. Hope this helps, Matt Wiener -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Sorkin Sent: Friday, July 15, 2005 8:48 AM To: [email protected] 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: [EMAIL PROTECTED] [[alternative HTML version deleted]] ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
