How would I create my own 'unique' function without using the built in unique?

I understand that the built in Unique function is stating that whatever function you define as unique is the same data set but without repetitions.

should I create a function file such as

function[unique,c] = myuni_1(A)

rows(A)= size(A,1);

columns(A) = size(A,2);

and then proceed to define the rows and columns as itself? I'm a bit confused here.

[the cyclist]

Why would you want to do this? Is this a homework assignment?

[Alexander]

My TA mentioned my professor may ask a question like this on my final exam and I would like to be prepared for anything. Also, my own curiosity is driving me to ask it.

I've looked at the function file on Matlab and it is a very long code. I'm curious if this is even possible with an alternative method that uses less code.

[Jan]

What exactly should your function do? Which types of input are expected? What is the 2nd output c? Please do not let us guess the details.

Notice that "rows(A)= size(A,1);" is no valid Matlab syntax.

Answer 1

[Jan]

A short version:

function U = myUnique(A)
[As, SV] = sort(A(:));
UV(SV)   = ([1; diff(As)] ~= 0);  % [1, As(2:nA) - As(1:nA-1)];
U        = A(UV);

[Alexander]

works like a charm, i was using 3 different for loops and trying to sort each one by the size of A but got nothing.

Thank you friend!

Answer 2

[Walter Roberson]

Suppose you have two "bags", A and B. Start with A empty.

If B is empty, you are done and A holds the unique values. Otherwise, take one one item, C, out of B (removing it from B). Is there already a copy of C in A? If there is, then throw away C. Otherwise, add C to A. Now restart this paragraph.

[Alexander]

im just confused about how to pull out a value and place it into the new matrix

Answer 3

[Sean de Wolski]

How about this?

x = [1 2 3 3 3 3 2 4 5];
[uv,ia] = intersect(x,x)