[R] "hist" combines two lowest categories -- is there a workaround?
Dieter Menne
dieter.menne at menne-biomed.de
Thu Jan 31 08:58:42 CET 2008
Ben Fairbank <BEN <at> SSANET.COM> writes:
>
> When preparing a series of histograms I found that hist was combining
> the two lowest categories or bins, 1 and 2. Specifying breaks, as
> illustrated below, resulted in the correct histogram:
>
> values <- sample(10,500,replace=TRUE)
>
> hist(values)
>
> hist(values,breaks = 0:10)
>
> Apparently, the number of values strictly less than 1 is shown in the
> first bin (and since none is less than 1, the value is 0), while the
> other bins appear to show the number of values less than or equal to the
> bin's upper bound. Is there a setting that will show the number of
> values less than or equal to the first bin's upper bound?
>
For irregular spacing, it's best when you do the factoring first, for example
with cut; and use histogram (lattice), which is more flexible than hist. Below
an example I use for age groups:
Dieter
-----------------------
library(lattice)
set.seed(4711)
age = floor(rnorm(100,50,15))
ageg = cut(age %/% 10 *10,c(0,seq(20,70,10),100),included.lowest=TRUE,
right=FALSE, ordered_result=TRUE)
# default plot
histogram(~ageg)
# if you really need it:
levels(ageg) = c("<20","20-29","30-39","40-49","50-59","60-69","70+")
histogram(~ageg)
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