Hello,
I have finally solved this riddle while reading the source code of boxplot
in axes.py file. And yes whisker plotting is done different than I expect.
When I assigned "whis" keyword to 3.0 the lower whisker is plotted on the
right spot. And Josh, yes you were right, it did plot the lower whisker as
seen on my very first uploaded image.
Still a question stays in my mind: How do you decribe box-whisker plots in
your writing while using matplotlib's boxplot command? It uses 25, 50, 75th
percentiles of the data for sure, but apart from what I expected whiskers
are not at 5th, and 95th percentiles of the data respectively.
Could someone please comment on this?
Gökhan
On Wed, May 13, 2009 at 8:43 PM, Gökhan SEVER <gokhanse...@gmail.com> wrote:
> One more point to add.
>
> I issued one more boxplot with prctile(data) (a mlab command which boxplot
> calls internally to calculate percentiles) as an argument to it.
>
> Guess what?
>
> I get almost the same as in initially I have :) without a lower whisker.
>
> I don't know I am confusing myself or is it the data...
>
> Gökhan
>
>
>
> On Wed, May 13, 2009 at 7:56 PM, Gökhan SEVER <gokhanse...@gmail.com>wrote:
>
>> Ok,
>>
>> With this figure, it is clearer to see what's wrong with two of my
>> boxplots. I pull the original data and feed boxplot with it.
>>
>> The 1st boxplot is using only quartiles and the next is providing the
>> actual data array.
>>
>> http://img140.imageshack.us/img140/4705/boxplots.png
>>
>> To me the second boxplot seems more convenient to put an academic paper.
>> What do you think? These boxplots only show the variation in true air speed
>> of a small leg of a research flight.
>>
>> Would there be a better representation of in addition to / as an
>> alternative boxplotting?
>>
>> Gökhan
>>
>>
>>
>> On Wed, May 13, 2009 at 1:41 PM, Gökhan SEVER <gokhanse...@gmail.com>wrote:
>>
>>> Thank you for the response once again.
>>>
>>> That's why I am suspecting actually the raw data. At the problem points
>>> there might be not included values or missing values where not exist on the
>>> normal plots.
>>>
>>> I will find the original data and feed boxplot with it to see how it
>>> effects the final result.
>>>
>>> Gökhan
>>>
>>>
>>>
>>> On Wed, May 13, 2009 at 12:58 PM, Josh Hemann <jhem...@vni.com> wrote:
>>>
>>>>
>>>> Thanks for sending the data and code. After playing around some I still
>>>> don't
>>>> have a confident guess as to the problem (or solution), but here is what
>>>> I
>>>> would look at more...
>>>>
>>>> I issued plot(d[i][8:]) for i 0,1,...11 and looked at the shape of
>>>> the
>>>> lines. For the two problem boxes, the plots of the associated data have
>>>> steep jumps between the 5th and 25th percentiles, when compared with the
>>>> data associated with the "good" boxes. So, what you have calculated as
>>>> the
>>>> 5th and 25th percentiles are not necessarily calculated by boxplot as
>>>> such
>>>> because boxplot does not know that you are handing it percentiles of
>>>> your
>>>> underlying data: boxplot actually computes the percentiles assuming that
>>>> the
>>>> input _is_ the raw data. I would guess that if you gave boxplot the raw
>>>> data
>>>> you would not see this issue of missing whiskers.
>>>> --
>>>> View this message in context:
>>>> http://www.nabble.com/One-more-question-regarding-to-boxplotting-tp23508395p23526653.html
>>>> Sent from the matplotlib - users mailing list archive at Nabble.com.
>>>>
>>>>
>>>>
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>>>
>>
>
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