# How to generate a histogram distribution with height function

According to the Mathematica documentation the HistogramList command allows to specify a height function fh, as third argument, that allows to compute the height based on the bin location and the bin count.

HistogramList[data,bspec,fh]


The command HistogramDistribution seems to be related but, according to the documentation, has only the binning options of HistogramList.

Is it possible to influence the height of the bins of a HistogramDistribution or to generate such a distribution from a HistogramList?

Another option would be to change the HistogramDistribution after creating it. The meaning of the elements of this structure seems quite obvious, but I lack knowledge how to change the structure. Trying to change it in the obvious way, histdist[] = {{...}} seems to break it.

• Do you really mean HistoryList and HistoryDistribution? – bill s Apr 20 '16 at 20:02
• Does the example in HistogramList >>Scope >> Height Specifications help? – kglr Apr 20 '16 at 20:20
• @bill HistogramList and HistogramDistribution – highsciguy Apr 20 '16 at 20:53

Update: You can replace the vector of PDFValues (i.e., Part (2,1)) of the DataDistribution object returned by HistogramDistribution with a vector that has the same length and sum.

data1 = RandomVariate[NormalDistribution[], 100];
D1 = HistogramDistribution[data1];
D2 = D1;
D2[[2, 1]] =  N@Total[D1["PDFValues"]]
Normalize[RandomInteger[10, {Length@D1["PDFValues"]}], Total];

D1["PDFValues"]


{0.02, 0.18, 0.38, 0.24, 0.14, 0.02, 0.02}

D2["PDFValues"]


{0.236842, 0.105263, 0.184211, 0.263158, 0.157895, 0.0526316, 0.}

Row[DiscretePlot[PDF[#, x], {x, -4, 4, .01}, ImageSize -> 300]& /@ {D1, D2}, Spacer] Through[{Mean, Median, Variance,  Moment[#, 2] &}@#] & /@ {D1, D2}


{{-0.06, -0.210526, 1.44973, 1.45333},
{-0.342105, -0.142857, 2.47946, 2.59649}}

Replace Normalize[RandomInteger[10, {Length@D1["PDFValues"]}], Total] with your choice of a vector that has appropriate length and sum.

Previous version:

From Histogram >> Details: And from HistogramList >> Details: And mimicking the example in HistogramList >> Scope >> Height Specifications

data = RandomVariate[NormalDistribution[0, 1], 100];

accumulatedCount[bins_, counts_] := Accumulate[counts]
Row@{Histogram[data, {1}, ImageSize -> 300],
Histogram[data, {1}, accumulatedCount, ImageSize -> 300]} we can construct custom height functions like:

foo1[bins_, counts_] := bins[[All, 1]]^2;
foo2[bins_, counts_] := Range[Length@counts];

Row@{Histogram[data, {1}, ImageSize -> 300],
Histogram[data, {1}, foo1, ImageSize -> 300],
Histogram[data, {1}, foo2, ImageSize -> 300]} The only requirement is that the height function returns a list of length that is equal to the number of bins:

See also: this answer to a related question for an example of how to construct a custom 3D height function for Histogram3D.

• Thanks, this tells me how to use the height function of HistogramList but I need a HistogramDistribution, not only to plot a histogram but also for statistical operations (strictly speaking I do not need it normalized). – highsciguy Apr 20 '16 at 20:56