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List all the possible combinations of three numbers from a given sample.

I have to work out and write down all the possible combinations of three numbers can be extracted (without repetition) from 80.

as an illustration:

there is only one group of three numbers in 3 (1,2,3)
there are four groups of three numbers in 4 (1,2,3  1,2,4  1,3,4  2,3,4)
there are 10 groups of three numbers in 6

I have for the calculation =COMBIN(80, 3) for excel which gives me 18,424 possibilities, so I know how many combinations are possible

I need code that will list all them written out in a spreadsheet in an list probably in a text document

I would be very grateful for help
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Europa MacDonald
Asked:
Europa MacDonald
1 Solution
 
TommySzalapskiCommented:
This is a duplicate of http:Q_28019535.html
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wilcoxonCommented:
Simple to do...

my @arr = #list of 80 numbers - either entered directly in code or read from file
open OUT, ">output.csv" or die "could not write output: $!";
for my $i (0..79) {
    for my $j (($i+1)..79) {
        for my $k (($j+1)..79) {
            print OUT "$i,$j,$k\n";
        }
    }
}
close OUT;

Open in new window

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Europa MacDonaldChief slayer of dragonsAuthor Commented:
TommySzalapski

it is a duplicate because I was advised to try Perl, so I reposted from excel to Perl
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tel2Commented:
Hi Michael,

wilcoxon's code looks good to me, except:
- I don't see the point of line 1, since @arr is not referenced elsewhere.
- From your examples, it looks as if you want numbers to be 1 to 80, not 0 to 79.

Here's the code with those minor adjustments:
#!/usr/bin/perl

open OUT, ">output.csv" or die "Could not write output: $!";
for my $i (1..80) {
    for my $j (($i+1)..80) {
        for my $k (($j+1)..80) {
            print OUT "$i,$j,$k\n";
        }
    }
}
close OUT;

Open in new window

Both scripts produce 82,160 rows of output, which is what =COMBIN(80, 3) gives me when I run it in Excel 2003.
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wilcoxonCommented:
Good point - typo in my code.  It says "from 80 numbers" so I'm assuming it is not simply the numbers 1-80 (if it is simply 1-80 then tel2's changes to my code will work).

my @arr = #list of 80 numbers - either entered directly in code or read from file
open OUT, ">output.csv" or die "could not write output: $!";
for my $i (0..79) {
    for my $j (($i+1)..79) {
        for my $k (($j+1)..79) {
            print OUT "$arr[$i],$arr[$j],$arr[$k]\n";
        }
    }
}
close OUT;

Open in new window

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TommySzalapskiCommented:
it is a duplicate because I was advised to try Perl, so I reposted from excel to Perl
What you could do next time is just hit the 'Request Attention' button and ask the Admins to add the Perl zone to the old question. That will generate emails to all the Perl experts asking them to check out your question.

I still don't see why you need something other than Excel for this though for 82k possibilities. Try doing it with the VBA code I posted (it's very similar to the Perl code here). It should work.
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FishMongerCommented:
There are a number of modules on cpan that does this for you very easily.

Unless I'm misunderstanding what you want, I think you'll end up with more combinations than what you think.

Here's my test script.
#!/usr/bin/perl

use strict;
use warnings;
use Math::Combinatorics;

my @set = 1..6;
my $combinat = Math::Combinatorics->new(count => 3, data => [@set]);

my $cnt;
while(my @permu = $combinat->next_combination){
    print join(' ', @permu)."\n";
    $cnt++;
}

print "\n$cnt\n";

Open in new window


Output of:
c:\testing>permutations.pl
6 5 4
6 5 3
6 5 2
6 5 1
6 4 3
6 4 2
6 4 1
6 3 2
6 3 1
6 2 1
5 4 3
5 4 2
5 4 1
5 3 2
5 3 1
5 2 1
4 3 2
4 3 1
4 2 1
3 2 1

20
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GwynforWebCommented:
In Java or C++ like syntax it is, (this is JavaScript)

<script>

n=5
for (i=1;i<=n;i++)
 for (j=i+1;j<=n;j++)
   for (k=j+1;k<=n;k++)
     document.write(i +' '+ j+ ' '+ k +"<br>")

</script>

Open in new window

You can run this by copying and pasting into Notepad, saving as a .htm and opening in a browser.

Test n=5
1 2 3
1 2 4
1 2 5
1 3 4
1 3 5
1 4 5
2 3 4
2 3 5
2 4 5
3 4 5
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DaneanCommented:
I like the Java version where you can open the list in a browser.  Is there also a way to send the output list to a txt file with the java script?
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