From: Ted Harding <Ted.Harding_at_manchester.ac.uk>

Date: Mon, 19 May 2008 10:31:24 +0100 (BST)

E-Mail: (Ted Harding) <Ted.Harding_at_manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861

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. Received on Mon 19 May 2008 - 09:33:40 GMT

Date: Mon, 19 May 2008 10:31:24 +0100 (BST)

Hi Folks,

I'd like to know how hist() decides how many cells to use
when it ignores my "suggestion" to use say 'hist(...,breaks=50)'.

For instance, for one of these simulations, the 8 different values of length(H$breaks) are:

70, 44, 38, 68, 50, 40, 46, 45

In the last three cases the number is a suggestion only.

B)

The default for 'breaks' is '"Sturges"': see 'nclass.Sturges'.

If I look at the code for nclass.Sturges() I see

function (x) ceiling(log2(length(x)) + 1)

and, for length(X) = 10000, this gives 15. This is not related to any of the numbers of breaks I actually got, in any way obvious to me.

So:

Question 1: hist() has apparently ignored my "suggestion" of
"break=50". Why? What is the criterion for ignoring?

Question 2: Presumably, if it ignores the "suggestion", it does something else, of its choice. I would then, perhaps, expect it to fall back to its default, which is (allegedly) Sturges. But the result from nclass.Sturges looks different from what it actually did. So what did it actually do, and how did it decide on this?

With thanks,

Ted.

E-Mail: (Ted Harding) <Ted.Harding_at_manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861

Date: 19-May-08 Time: 10:31:20 ------------------------------ XFMail ------------------------------ ______________________________________________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. Received on Mon 19 May 2008 - 09:33:40 GMT

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