How to find similar users to a target user?

Hi all.

I have an example array (which contains 8 users). I have calculated similarity value for all the users who do not have a value '1' except for themselves. Like in example array, 4 is the only user who do not have a value of 1 for any other user expect for himself (as shown in array 'a'). So i have calculated Similarity of 4 with all other users using some mathematics. Which results in Similarity array:

    example= [1,1,1,0,0,0,0,0;0,1,1,1,0,0,0,0;0,0,1,0,1,0,0,0;0,0,0,1,0,0,0,0;0,0,0,0,1,1,0,0;0,0,0,0,0,1,1,1;1,0,0,0,1,0,1,1;0,0,0,1,0,0,0,1]
    Similarity = {1;0.8;1;0.9;0.96;1;-0.8}
    a= [4]

In similarity array, 1 is similarity of 4 with 1, 0.8 is for 4 and 2, 1 is for 4 and 4 and 3, 0.9 is for 4 and 5 and so on until user 8.

Now i want to extract the users whose similarity with 4 is greater than 0. Like here user 8 has value less than 0, so it will be eliminated and result will look like this: (containing all the similar users)

    result ={1,2,3,5,6,7}

And similarly how we can perform this if there are more numbers in array 'a' along with 4. I hope my question is clear.

Thanks in anticipation.

Answer 1

[Paul Siefert]

You can find values above 0 with the "find" function (type in command window: doc find). To search inside cells you can "cell2mat" before that or do it in a loop.

In oder to process more persons you better use correct indexing. You could create a cell with size of number of persons and save Similarity values inside the corresponding cells. Then you can loop though the length of a using the values of a.

a = [4 6];

Similarity = cell(2,8);
Similarity{1,a(1)} = {1;0.8;1;1;0.9;0.96;1;-0.8};
Similarity{1,a(2)} = {0.2;0.6;-1;0.4;0.84;-0.96;-0.68;0.7};

for i = 1:length(a)
    Person = a(i);
    Similarity{2,Person} = find(cell2mat(Similarity{1,Person}) > 0);
end

In this example you create a Similarity cell, the first row is for Similarity values, the second for finding values above 0.

The loop runs from 1 to the length of you a array, the person number is defined as a(i). This is used to save the values to the second row.

Hope this helps Paul

[lucksBi]

Thanks alot for help.