Re: BinCounts
- To: mathgroup at smc.vnet.net
- Subject: [mg60931] Re: [mg60918] BinCounts
- From: "Carl K. Woll" <carl at woll2woll.com>
- Date: Tue, 4 Oct 2005 01:24:58 -0400 (EDT)
- References: <200510030806.EAA00260@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Alberto Verga wrote:
> Why does BinCounts[] give lists with unpredictable Dimensions[]?
>
> With[{n = 205}, ll = RandomArray[NormalDistribution[0, 1], {n}];
> Dimensions[BinCounts[ll, {Min[ll], Max[ll], (Max[ll] - Min[ll])/n}]]]
>
>
>
> You may try different values of n (or the same n and different samples of
> the random numbers), and verify that the lenght of the list depends on the
> random realization: somtimes you get n, somtimes n+1.
>
You get different results because of numerical error associated with using
inexact numbers like machine numbers. Instead, use exact arithmetic or add a
fudge factor. Assuming you want to get n bins, the following approach will
always do so for reasonable data:
BinCounts[ll, {Min[ll],Max[ll],(Max[ll]-Min[ll])/n + $MachineEpsilon}]
Alternatively, you could use Rationalize by replacing Min[ll] (and Max[ll])
with Rationalize[Min[ll],0] etc.
> Alberto Verga
>
>
> Alberto Verga
>
> IRPHE - Université de Provence
>
> 49, rue F. Joliot-Curie, BP 146,
>
> 13384 Marseille, France
>
>
>
>
Carl Woll
Wolfram Research
- References:
- BinCounts
- From: Alberto Verga <Alberto.Verga@laposte.net>
- BinCounts