[R] Histogram

[David Carlson]

Good question. It turns out that the manual page does not tell
the whole story. Looking at the source code for hist.default,
the function starts with the number of breaks suggested by
nclass.Sturges(), but then this number (or any other number of
breaks that you specify) is passed to pretty() along with the
maximum and the minimum values of the data (ie range(data)) to
create "pretty" break intervals. In your example,
nclass.Sturges() always recommends 8 breaks, but the number of
the breaks changes based on the minimum and maximum values. So
the only way to get exactly the number of breaks you want is to
specify the break intervals yourself.

David Carlson


-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of philippe
massicotte
Sent: Wednesday, September 4, 2013 3:02 PM
To: Rui Barradas
Cc: r-help at R-project.org
Subject: Re: [R] Histogram

Thank you everyone.
Try executing this:
replicate(100, length(hist(rnorm(100), nclass = 10)$counts))
I'm still not sure why the number of bins (classes) is not
consistent. 
Thank in advance.

> Date: Wed, 4 Sep 2013 20:27:36 +0100
> From: ruipbarradas at sapo.pt
> To: pmassicotte at hotmail.com
> CC: r-help at r-project.org
> Subject: Re: [R] Histogram
> 
> Hello,
> 
> See the arguments 'right' and 'include.lowest' of ?hist.
> To give what you want, try instead
> 
> h1 <- hist(1:10, 10)  # counts are 2, 1, 1, ...
> h2 <- hist(1:10, breaks = 0:10)  # all counts are 1
> 
> 
> and see the difference between h1 and h2, components 'breaks'
and 'counts'.
> 
> Hope this helps,
> 
> Rui Barradas
> 
> Em 04-09-2013 19:34, philippe massicotte escreveu:
> > Hi everyone.
> > I'm currently translating some Matlab code into R. However,
I realized that the hsit function produce different results in
both languages.
> > in Matlab, hist(1:10, 10) will produce 10 bins with a count
of 1 in each, but in R it will produce 9 classes with count of
2,1,1,1,1,1,1,1,1.
> > I'm a bit embarrassed to ask such question, but why R is not
producing 10 classes as requested?
> > Thanks in advance,Phil 		 	   		
> > 	[[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at 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.
> >
 		 	   		  
	[[alternative HTML version deleted]]

______________________________________________
R-help at 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.