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MathGroup Archive 2005

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Re: Weighted histogram

  • To: mathgroup at smc.vnet.net
  • Subject: [mg62287] Re: Weighted histogram
  • From: kalymereau at yahoo.fr
  • Date: Sat, 19 Nov 2005 05:54:11 -0500 (EST)
  • References: <dliv00$g1b$1@smc.vnet.net><dlkcct$pr0$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Thank you for the answers but it seems that neither the solution of Bob
nor the one of Ray works.

I want that each value in a be weighted by both its occurrence in the
list a and by the corresponding weight in w. In other words, with
a={1,1,1,2,3,4} and w={1,1,1,1,2,1}
I want the histogram of b={1,1,1,2,3,3,4}

Obviously this is not what does Bob's proposal.

When w is a list of integers it is if course very easy to construct b
from a and w: just duplicates the elements of a according to their
weights in w.

When a is a list of integers then it seems that the solution of Ray
works (although I don't really understand it).

But when both a and w are lists of real numbers, then it doesn't work.

It is possible to construct a binning and then to fill each bin by the
corresponding values in a ponderated by the weights in w. But the tests
I made in this direction were very slow for large lists, and I would
like something more natural.

It seems to me to be a very basic problem of data analysis, any other
idea ?

Thanks.


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