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Re: Histogram

  • To: mathgroup at smc.vnet.net
  • Subject: [mg108749] Re: Histogram
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Tue, 30 Mar 2010 05:01:01 -0500 (EST)

On 3/29/10 at 6:58 AM, lambaugh at gmail.com (Jim Lambaugh) wrote:

>The reason why I am asking (I should have included this in my first
>post) is because I am trying to find a way to determine the size of
>the largest gap between the values I have in my list.

Hmm... I don't see how a histogram with infinitely small bins
would help with this. Finding the largest gap between a list of
values is easily done as follows:

In[1]:= data = RandomReal[1, 10];

In[2]:= Max@Differences[Sort@data]

Out[2]= 0.292657

But if you want something that simulates a histogram with
infinitely small bin widths you could do something like:

data = RandomReal[1, 100];
f = Interpolation[Transpose@{Sort[data], (Range[100] - .5)/100},
    InterpolationOrder -> 1];

f will be the cumulative distribution function. Note, using
InterpolationOrder->1 is needed to ensure f is never decreasing.
Since a histogram is simply the probability density function
which is the derivative of the cumulative distribution function

Plot[(f[x+.0001]-f[x])/.0001, {x, 0, 1}]

will be the desired histogram.

Note, because of using InterpolationOrder->1, the derivative is
not continuous. So, the resulting plot will not be a smooth
curve. It is possible to achieve this. But that requires a more
sophisticated approach to estimating the probability density
function than a simple histogram.



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