On 26-Dec-09 15:33:45, James Rome wrote: > histogram(~(Arrival4) | as.factor(Hour), type="count", > breaks=16,ylab="Arrival Count", > xlab="Arrival Rate/4",main="Friday EWR A22R D22L Configiration", > layout=c(6,4), par.strip.text=list(cex=0.7)) > > Why do I get plots with different bar widths? See attached. > > Thanks, > Jim Rome
Read the 'breaks' section under "Arguments:" in ?histogram in the lattice package. If you choose to use the default method: breaks = seq_len(1 + nlevels(x)) - 0.5 when 'x' is a factor, and breaks = do.breaks(endpoints, nint) otherwise, or if you specify the numerical break-points explicitly, as for instance in breaks = (0:15) then the same set of break-points will be used for each histogram across all panels. If you use another specification, such as yours: breaks=15 then: "Other values of 'breaks' are possible, in which case they affect the display in each panel differently." which is what you are seeing. Compare the three histogram plots from the following code: X <- c(rnorm(100),rnorm(50,1.0,0.5),rnorm(25,-1.0,0.5),rnorm(10)) F <- factor(c(rep(0,100),rep(1,50),rep(2,25),rep(3,10))) # The default: histogram(~X | F) # Your choice (number of breaks) histogram(~X | F, breaks=10) # Explicit specification of break-points: histogram(~X | F, breaks=0.5*(-6:6)) Hoping this helps, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 26-Dec-09 Time: 18:28:32 ------------------------------ XFMail ------------------------------ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
