Plot smooth cumulative distribution function using MATLAB

Question

How is it possible to make the following cumulative distribution function (CDF) curve smoother?

Here's my code, using cdfplot:

clear all; 
close all;
y = [0.75862069 0.666666667 0.882352941 0.875 0.736842105 0.566666667 0.703703704 0.6 0 0.730769231 0.714285714 0.625 0.675 0.693877551 0.731707317 0.558823529 0.679245283 0.740740741 0.785714286 0.789473684 0.615384615 0.6 0.739130435 0.576923077 0 0.75];
cdfplot(y)

The plot looks like:

Solution 1

data = [1 2 2 3 4];
dsum = sum(data);
normalized_data = data/dsum;

cdf = data;

for i = 1:length(data)
    cdf(i) = sum(normalized_data(1:i));
end

plot(cdf);

Is this what you are looking for?

Solution 2

data = [2 1 4 2 3];
sdata = sort(data);
plot(sdata,(0.5:length(sdata))./length(sdata),'-');

Solution 3

You can use the function ecdf:

[f,x] = ecdf(y);
plot(x,f);

Comments

[Dang Khoa]

What have you done in attempts to figure out the problem?

[ddayan]

yea:data = [1 1 1 4 5]; %# Sample data p1 = cdf('Normal',data,0,1); plot(p1);

[SecretAgentMan]

This appears to be an empirical CDF and therefore will not typically be smooth unless altered.