From gug at fnal.gov  Sat Nov  7 00:30:12 2009
From: gug at fnal.gov (gug at fnal.gov)
Date: Sat,  7 Nov 2009 00:30:12 +0100 (CET)
Subject: [Rd] Binning of integers with hist() function odd results (PR#14046)
Message-ID: <20091106233012.B2AB0282EF5A@mail.pubhealth.ku.dk>

Full_Name: Gerald Guglielmo
Version: 2.8.1 (2008-12-22)
OS: OSX Leopard
Submission from: (NULL) (131.225.103.35)


When I attempt to use the hist() function to bin integers the behavior seems
very odd as the bin boundary seems inconsistent across the various bins. For
some bins the upper boundary includes the next integer value, while in others it
does not. If I add 0.1 to every value, then the hist() binning behavior is what
I would normally expect. 

> h1<-hist(c(1,2,2,3,3,3,4,4,4,4,5,5,5,5,5))
> h1$mids
[1] 1.5 2.5 3.5 4.5
> h1$counts
[1] 3 3 4 5
> h2<-hist(c(1.1,2.1,2.1,3.1,3.1,3.1,4.1,4.1,4.1,4.1,5.1,5.1,5.1,5.1,5.1))
> h2$mids
[1] 1.5 2.5 3.5 4.5 5.5
> h2$counts
[1] 1 2 3 4 5

Naively I would have expected the same distribution of counts in the two cases,
but clearly that is not happening. This is a simple example to illustrate the
behavior, originally I noticed this while binning a large data sample where I
had set the breaks=c(0,24,1).



[Rd] Binning of integers with hist() function odd results (PR#14046)
gug at fnal.gov