Re: [matplotlib-devel] is R wrong? (boxplot)

[Paul H. <pmh...@gm...>]

Hey Yaroslav,

As the author of the fix and the recent overhaul to boxplots, I can say
with certainty that R is wrong! ;-)

More seriously, the main thing that I take away from Tukey's paper about
boxplots, is that there are many valid ways to draw them. I personally set
up the new boxplot functionality to take the most basic boxplot definition
very literally. My guess is that R is fudging those rules a bit for the
purpose of completeness, or aesthetics, or ...(?)

Perhaps one can look at the purpose of boxplots in two different fashions:
1) Matplotlib: show some of the data and some basic stats
2) R (I'm guession): show how the data are /probably/ distributed.

Obviously, I prefer #1. But I'm not going to say that #2 is wrong just yet.




On Sat, Feb 15, 2014 at 5:00 AM, Yaroslav Halchenko <sf...@on...>wrote:

> Dear Matplotlib gurus,
>
> Following the code to demonstrate recent(ish) fix for whiskers in boxplots:
> https://github.com/matplotlib/matplotlib/pull/1855 I have compared it
> against
> R's boxplot.  Description seems to correspond, and all the percentiles are
> the
> same in numpy and R (3.0.1) but R's boxplot seems to have extended IQR box
> and
> still have an upper whisker (corresponds to 9000, which is not within
> 75%+1.5*IQR), when it shouldn't:
>
> http://nbviewer.ipython.org/url/www.onerussian.com/tmp/boxplot-Python-vs-R.ipynb
>
> is R's plot incorrect or am I missing something (e.g. documented feature
> in R's boxplot) warranting such a difference?
>
> Thanks in advance
> --
> Yaroslav O. Halchenko, Ph.D.
> http://neuro.debian.net http://www.pymvpa.org http://www.fail2ban.org
> Senior Research Associate,     Psychological and Brain Sciences Dept.
> Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
> Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
> WWW:   http://www.linkedin.com/in/yarik
>
>
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