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Normalized histogram

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Normalized histogram

by

Arturo Serrano

 

28 Jan 2009 (Updated )

Same as histogram, but the area sum is 1.

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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)
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Comments and Ratings (22)
22 Nov 2014 ?

?

 
10 Jul 2013 R

R

it work fantastic:)how could we use histnorm to calculate normalized histogram for hsv histogram

Comment only
10 Jul 2013 R

R

 
10 Jul 2013 R

R

 
26 Apr 2013 Damien

Damien

thanks!!!

25 Mar 2013 arnold

arnold

nice one, thanks!

22 Mar 2013 Arturo Serrano

Arturo Serrano

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

Comment only
21 Mar 2013 Linpeng

Linpeng

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

13 Mar 2013 Arturo Serrano

Arturo Serrano

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

Comment only
12 Mar 2013 Bernoulli Lizard

Bernoulli Lizard

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

Comment only
22 Jun 2012 ww

ww

Fantastic :)

04 Sep 2011 Flavio Prattico

Flavio Prattico

Great!!!

18 Aug 2011 Bob

Bob

disregard above comment about the mean...

Comment only
18 Aug 2011 Bob

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);

13 Oct 2010 Anne Calder

Anne Calder

Thank you! Works perfect!

Comment only
04 Oct 2010 Arturo Serrano

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).

Comment only
03 Oct 2010 Anne Calder

Anne Calder

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

17 Jun 2010 Gustavo

Gustavo

 
05 Mar 2010 Shahzad Bhatti

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 ?

Comment only
25 Feb 2010 Ian Baldwin

Ian Baldwin

very useful

Comment only
16 Nov 2009 abdelhamid alhassi

abdelhamid alhassi

thanks very helpful

20 Feb 2009 Darcy Sabatino

Darcy Sabatino

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

Updates
22 Mar 2013

Updated the example.

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