# Computing CDF????

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Hi all,

Does anyone of you know how to calculate cdf plot using following data sets:

A = [10 10 10 5 3 3 3 2 0]; B = [10 10 10 5 5 3 3 2 2 2 1 0]; how can obtain cdf from A and B?

Best Regards Talha

##### 0 Comments

### Accepted Answer

Steven Lord
on 30 May 2018

If you're using release R2014b or later (for histcounts and histogram) or release R2015b or later (for histcounts2 and histogram2) you can specify the 'Normalization' argument with value 'cdf' to display the CDF of the data that you binned using the appropriate function.

Note that this doesn't find parameters for a particular distribution that were determined by fitting the distribution to your data. If you want to do that, take a look at some of the functions on this page in the documentation for Statistics and Machine Learning Toolbox, specifically those whose names end in "fit".

##### 1 Comment

Camilo Malagon Nieto
on 31 May 2018

Thank you for the update. Then the solution will be:

Given....

A = [10 10 10 5 3 3 3 2 0]; B = [10 10 10 5 5 3 3 2 2 2 1 0]

First merge the data in a new vector

X=[A,B]

The plot the Cumulative distribution histogram

histogram(X,'Normalization','cdf')

### More Answers (4)

Image Analyst
on 19 Dec 2011

Try this code. It's actually just two calls - one to hist() and one to cumsum(), but it's a full-fledged demo with all kinds of fancy plotting and does it for both A and B, so it looks long and complicated but it's actually not. (It only took about 3 minutes to code up this demo). Don't be afraid - just copy, paste, and run:

clc; % Clear the command window.

workspace; % Make sure the workspace panel is showing.

fontSize = 20;

A = [10 10 10 5 3 3 3 2 0];

B = [10 10 10 5 5 3 3 2 2 2 1 0];

% Compute the histogram of A and B.

[countsA, binsA] = hist(A);

[countsB, binsB] = hist(B);

% Compute the cumulative distribution function of A and B.

cdfA = cumsum(countsA) / sum(countsA);

cdfB = cumsum(countsB) / sum(countsB);

% Plot the probability distribution of A.

subplot(2,2, 1);

bar(binsA, countsA);

title('Histogram of A', 'FontSize', fontSize);

ylabel('Count A', 'FontSize', fontSize);

xlabel('Values of A', 'FontSize', fontSize);

grid on;

% Plot the probability distribution of B.

subplot(2,2, 2);

bar(binsB, countsB);

title('Histogram of B', 'FontSize', fontSize);

ylabel('Count B', 'FontSize', fontSize);

xlabel('Values of B', 'FontSize', fontSize);

grid on;

% Plot the cumulative distribution function of A.

subplot(2,2, 3);

bar(binsA, cdfA); % You can use plot() if you want to.

title('CDF of A', 'FontSize', fontSize);

grid on;

ylabel('Percentage A (/100)', 'FontSize', fontSize);

xlabel('Values of A', 'FontSize', fontSize);

% Plot the cumulative distribution function of B.

subplot(2,2, 4);

bar(binsB, cdfB); % You can use plot() if you want to.

title('CDF of B', 'FontSize', fontSize);

ylabel('Percentage B (/100)', 'FontSize', fontSize);

xlabel('Values of B', 'FontSize', fontSize);

grid on;

% Enlarge figure to full screen.

set(gcf, 'units','normalized','outerposition',[0 0 1 1]); % Maximize figure.

set(gcf,'name','Demo by ImageAnalyst','numbertitle','off')

##### 0 Comments

Ssssssss fffgffggg
on 9 Jul 2017

how to plot exp cdf with histogram?????

##### 2 Comments

Image Analyst
on 9 Jul 2017

Camilo Malagon Nieto
on 30 May 2018

Edited: Camilo Malagon Nieto
on 30 May 2018

This will be my answer:

There is not a function that automatically takes a data vector and creates a vector with CDF values.

You need first to see your data by plotting it with a histogram

hist(X)

then use the distribution tool to see what distributions may suit your data

disttool

then use the distribution fitting tool to see how that distribution actually fits your data

dfittool

Then create a new distribution Object that fits your data

NewDist=fitdist(X,'Normal');

Than use the new distibution to plot the CDF

cdfplot(NewDist)

if you need values from the CDF you will have to create a values vector and the values to plot and get the CDFs for them

t=0:0,1:10;

Xcdf = cdf(NewDist,t);

Then you can plot the same

plot(t,Xcdf);

##### 1 Comment

Camilo Malagon Nieto
on 30 May 2018

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