"bucketing" observations

-----Original Message-----
From: Dimitris Rizopoulos [mailto:d.rizopoulos at erasmusmc.nl] 
Sent: Monday, April 06, 2009 4:01 PM
To: Dan Dube
Cc: r-help at r-project.org
Subject: Re: [R] "bucketing" observations

try this:

dat <- data.frame(vals = rnorm(1000))
breaks <- quantile(dat$vals, seq(0, 1, .1)) dat$bucket <- 
cut(dat$vals, breaks, labels = FALSE, include.lowest = TRUE)


I hope it helps.

Best,
Dimitris


Dan Dube wrote:

is there a better way to bucket observations into 

more-or-less evenly 

sized buckets than this?  it seems like this must be a 

common operation:

dt = data.frame(points=rnorm(1000),bucket=NA)

breaks = quantile(dt$points,seq(0:1,.1)) for (i in 

2:length(breaks)) {

	if (i == 2) {
		ind = which(dt$points >= breaks[i-1] & dt$points <=
breaks[i])
	} else {
		ind = which(dt$points > breaks[i-1] & dt$points <=
breaks[i])
	}
	dt$bucket[ind] = i-1
}

thanks!

--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014