Normalized histogram

Same as histogram, but the area sum is 1.

Description

HISTNORM Histogram normalized
  [...] = HISTNORM(...) works like HIST, but the frequency is normalized so that area sum is 1.

  Bonus usage!
  [...] = HISTNORM(..., 'plot') plots and returns the output arguments. Be sure 'plot' is the last argument.

  Example:
      data = randn(1)+randn(1)*randn (10000, 1);
      [xo,no] = histnorm(data, 101, 'plot');
      hold on
      plot (no, normpdf(no, mean(data), std(data)), 'r');
      hold off

  See also: HIST.

  Copyright 2009 DWTFYW.

• MATLAB release: MATLAB 7.7 (R2008b)

[Damien]

thanks!!!

[arnold]

nice one, thanks!

[Arturo Serrano]

The *area* must sum up to 1.
Thanks for rating!

[Linpeng]

The columns sum up to 10 instead of 1. Any ideas?

[Arturo Serrano]

*Why* is not working? I don't see any problems. Maybe if you give some clues, we can help.

[Bernoulli Lizard]

This does not work. The height of my bins is on the order of 10^4. What is wrong?

[Shinobue111]

Fantastic :)

[Flavio Prattico]

Great!!!

[Bob]

disregard above comment about the mean...

[Bob]

Doesn't seem to work with non-zero mean data sets. I found that the code below works better. It can not handle the case where you specify your own bin widths. But it can handle a matrix of data.
e.g.: histnorm([randn(1e3,1) randn(1e3,1)+8],50)

function varargout = histnorm(varargin)

len = size(varargin{1});
n = len(2);
[xo,no] = hist (varargin{:});
binwidths = diff(no);
xonorm = xo/sum (xo .* (binwidths(1)*ones(size(xo))))*n;
bar(no,xonorm);

[Anne Calder]

Thank you! Works perfect!

[Arturo Serrano]

Hi Anne,
you can change the colors by setting properties from the matlab command window. This should does the trick:

>> set (findobj (gca, 'type', 'patch'), 'edgecolor', [0.5 0.5 0.5], 'facecolor', [0.1 0.1 0.1]);

Edgecolor and facecolor values are the RGB values for bin colors (you can use letters also as plot does).

[Anne Calder]

Super useful... was wondering if you can change the colors in the bins. This isn't working for me.

[Gustavo]

 

[Shahzad Bhatti]

It didn't work for me. It is giving same histogram as does hist ... I mean it is not normlizing !!!

@ Author - Any idea - what i am doing wrong ?

[Ian Baldwin]

very useful

[abdelhamid alhassi]

thanks very helpful

[Darcy Sabatino]

Very helpful. The histnorm() function is virtually as easy as the hist() function.