How to find the exact values in a column and make a computation according to the next column of it?

Hi; I have matrix that first column shows task numbers, second column shows the station numbers that tasks assigned and third column shows the machine types assigned to regarding stations..

For example:

A=

1 1 1

5 1 2

4 2 2

2 2 2

3 3 2

7 3 1

6 4 2

9 4 1

this matrix says that task 1 and task 5 assigned to workstation1 and machice type 1 and machine type 2 is neccesarry.

task 4 and task 2 assigned to workstation2 and only machine 2 is neccesarry and only 1 machine2 is neccasary (two tasks are assigned to one machine). Now I want to compute the machine numbers for the stations that :

mac=

2

1

2

2

Thanks in advance;

Regards..

Answer 1

[Guillaume]

It's not very clear what you're asking. If all you want is to know how many different machines are required for each station, it's simply:

A = [1 1 1
     5 1 2
     4 2 2
     2 2 2
     3 3 2
     7 3 1
     6 4 2
     9 4 1];
mac = accumarray(A(:, 2), A(:, 3), [], @(x) numel(unique(x)))

accumarray groups the machines by station and the anonymous function @(x) numel(unique(x)) counts the number of unique machine for each station.

Note that the code will only work correctly if the stations are consecutive integers starting at 1. If not:

[station, ~, subs] = unique(A(:, 2));
mac = accumarray(subs, A(:, 3), [], @(x) numel(unique(x)))

will work regardless of the station values.

[bilgesu ak]

Thank you Guillaume very much. My station numbers starts from 1 and it works right..

With my regards...