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Re: Re: How to get data from Histogram

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97481] Re: [mg97455] Re: [mg97367] How to get data from Histogram
  • From: Brett Champion <brettc at wolfram.com>
  • Date: Sat, 14 Mar 2009 05:36:55 -0500 (EST)
  • References: <200903130953.EAA20401@smc.vnet.net>

On Mar 13, 2009, at 4:53 AM, Bob Hanlon wrote:

> h = Histogram[RandomReal[NormalDistribution[0, 1], 200]]
>
> Just look at the FullForm and extract whatever you want. The bin  
> interval and count are
>

The method used in the documentation, as pointed out by DrMajorBob is  
better.  It gets the information from a documented behavior of  
Histogram (namely, what the third argument can be.)

The internal form of the graphic returned by Histogram is not  
documented and is subject to change from version to version.  For  
example, V7.0.1 has a change from V7.0.0 in how the styles are applied  
to Histogram's bars so that the size (in bytes) of the graphic is  
smaller (by about 20% for a simple example I just tried.)

Brett Champion
Wolfram Research



> bd = Cases[h, RectangleBox[{bl_, _}, {br_, c_}] :> {{bl, br}, c},  
> Infinity]
>
> {{{-(5/2), -2}, 5}, {{-2, -(3/2)}, 8}, {{-(3/2), -1}, 13},
>   {{-1, -(1/2)}, 36}, {{-(1/2), 0}, 37}, {{0, 1/2}, 43},
>   {{1/2, 1}, 23}, {{1, 3/2}, 21}, {{3/2, 2}, 7}, {{2, 5/2}, 5},
>   {{5/2, 3}, 2}}
>
> bins = bd[[All, 1]] // Flatten // Union
>
> {-(5/2), -2, -(3/2), -1, -(1/2), 0, 1/2, 1, 3/2, 2, 5/2, 3}
>
> counts = bd[[All, 2]]
>
> {5,8,13,36,37,43,23,21,7,5,2}
>
> counts == Cases[h, Tooltip[_, Style[label_, __]] :> label, Infinity]
>
> True
>
>
> Bob Hanlon
>
> ---- Jozef Pulko <jozef.pulko at googlemail.com> wrote:
>
> =============
> Well that is exactly what I was looking for. Thanks!!
>
> SOLUTION:
> h = Histogram[RandomReal[NormalDistribution[0, 1], 200]]
> counts = Cases[h, Tooltip[_, Style[label_, __]] :> label, Infinity]
>
> However I only get number of counts in a bin.. is it possible to  
> somehow extract also the bin positions?
>



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