Hi, I am using the following R version: > R version 2.4.1 (2006-12-18) > Copyright (C) 2006 The R Foundation for Statistical Computing > ISBN 3-900051-07-0 I believe I found a bug in the 'hist' function, when 'probability=TRUE'. I looked in the archives and I came across problems with the 'hist' functions (e.g., bug PR# 944, posted in 2001), however, a quick search did not find the exact problem I a found. A brief description of the issue follows. > z<-rnorm(10) > z [1] 0.51649608 -0.20676010 0.65951365 0.46733006 0.02084361 0.18323525 [7] -0.21522566 0.29597667 0.81549448 0.26252625 > hist(z,breaks=seq(-1,1,by=.25)) > hist(z,breaks=seq(-1,1,by=.25),probability=TRUE) I think the values on the Y axis are messed up, e.g., it should top at 0.3 (relative frequency) for the bin [0.25 0.50). How is 'Density' computed? best regards, Edo ------------------------------------------------- Edo Airoldi, Ph.D. Department of Computer Science & Lewis-Sigler Institute for Integrative Genomics Princeton University, NJ 08544 609-258-8326 (lab phone) 609-258-8004 (fax)
On 2/14/2007 5:51 PM, Edo Airoldi wrote:> Hi, I am using the following R version: > > > R version 2.4.1 (2006-12-18) > > Copyright (C) 2006 The R Foundation for Statistical Computing > > ISBN 3-900051-07-0 > > I believe I found a bug in the 'hist' function, when > 'probability=TRUE'. I looked in the archives and I came across > problems with the 'hist' functions (e.g., bug PR# 944, posted in > 2001), however, a quick search did not find the exact problem I a > found. A brief description of the issue follows. > > > z<-rnorm(10) > > z > [1] 0.51649608 -0.20676010 0.65951365 0.46733006 0.02084361 > 0.18323525 > [7] -0.21522566 0.29597667 0.81549448 0.26252625 > > hist(z,breaks=seq(-1,1,by=.25)) > > hist(z,breaks=seq(-1,1,by=.25),probability=TRUE) > > I think the values on the Y axis are messed up, e.g., it should top > at 0.3 (relative frequency) for the bin [0.25 0.50). How is 'Density' > computed?It's not relative frequency, it's density: relative frequency per unit of x. The upper limit would be 4 with a step size of 0.25 (if all the observations fell in one interval). Duncan Murdoch