Combinational Calculation generation

[Ken Shamrock]

Hi,
If I have a series of keyword(number) like this:
1 2 3 4
How can I generate this?
1: 2 3 4
1: 2 3
1: 2 4
1: 3 4
1: 2
1: 3
1: 4
1 2: 3 4
1 2: 3
1 2: 4
1 3:...
1 4:...
2 3:...
3 4:...
Is there any existing code that can help me do this? Thanks x1000!!

[Steve Deadsea]

What you have is pretty close to all the combinations of your keywords. I'm not sure what the colons you have are for. Maybe you can modify some simple code that prints out all combinations to do what you want.

class Combo {
  public static void main(String[] args){ 
    printCombo(args);  
  }
  
  public static void printCombo(String[] keys){
    String[] working = new String[keys.length]; 
    printCombo(keys, working, 0);
  }
  
  private static void printCombo(String[] keys, String[] working, int last){
    for (int i=last; i<keys.length; i++){
      working[i] =  keys[i]; 
      printCombo(keys, working, i+1);
      working[i] = null;  
    }
    for (int i=0; i<working.length; i++){
      if (working[i] != null){
        System.out.print(working[i] + " ");
      }
    }
    System.out.println();
  }
}

When run with:
java Combo 1 2 3 4
it produces:
1 2 3 4
1 2 3
1 2 4
1 2
1 3 4
1 3
1 4
1
2 3 4
2 3
2 4
2
3 4
3
4

[Ken Shamrock]

Steve. Thanks very much! You are really helpful! I'm bad at recursion.

[John Smiley]

Hi Ken
What are the colons for?
John Smiley

[Ken Shamrock]

John.
Actually these are association rules. colon means implies (->
1-> 2 3 4