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enter image description here

Note: the diagram above shows a partition into groups of 5 (the columns). The horizontal box denotes the median values of each partition. The 'P' item indicates the median of medians.

Most of the researches that I saw have this picture in Selecting their "P" and it always have an odd numbers of elements. But What if the numbers elements you have are even?

ex.

 1  2  3  4  5  6  7  8  9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

how do you get your "P" in an even set of elements?

KC-Chan
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  • What are these researchers doing in this question? And sorry, what is the question actually? :) – jsalonen Jul 15 '13 at 22:40
  • My "P"? What is my "P" and is it any different from your "P"? If you have these definitions, please provide them with your question for clarity! – jsalonen Jul 15 '13 at 22:42
  • The picture above has an odd number of elements that's why it is easy to track the "P". While the numbers below are my given, and I don't know how to get the "P" with even numbers of elements. @jsalonen – KC-Chan Jul 15 '13 at 22:50
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    See my edit for a brief explanation of what "P" is. – hatchet - done with SOverflow Jul 15 '13 at 22:52
  • Thank you for that :) How do you know "P" in an even set of elements like the example below? – KC-Chan Jul 15 '13 at 22:54

1 Answers1

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This explanation gives the detail I think you're looking for:

https://www.cs.duke.edu/courses/summer10/cps130/files/Edelsbrunner_Median.pdf

The median of the set plays a special role in this algorithm, and it is defined as the i-smallest item where i = (n+1)/2 if n is odd and i = n/2 or (n+2)/2 if n is even.

hatchet - done with SOverflow
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