Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

All combinations from multiple arrays

Posted on 2004-04-12
6
1,035 Views
Last Modified: 2008-03-10
This shouldn't be too difficult, but... How can I get all possible combinations from multiple string arrays? The number of items in any array will be 1..n and number of arrays 1..n

E.g. first array could be:
word11
word12

second array:
word21
word22
word23

from these I should be able to get a new array:
word11 word21
word11 word22
word11 word23
word12 word21
word12 word22
word12 word23
0
Comment
Question by:mmiika
6 Comments
 
LVL 4

Expert Comment

by:Jarodtweiss
ID: 10804295
Not sure to understand... You want to loop on your arrays to get all the items ?

int i, j;

for (i = 0; i < myFirstArray.Count; ++i)
{
  for (j = 0; j < myFirstArray(i).MySecondArray.Count; ++j)
  {
    console.WriteLine(myFirstArray(i).MySecondArray(j).ToString());
  }
}
0
 
LVL 3

Author Comment

by:mmiika
ID: 10804382
This seems to work...

private ArrayList loopThroughArrays(ArrayList WordLists)
{
      ArrayList ret = new ArrayList();
      int wordCount = WordLists.Count;
      int lastWord = wordCount-1;
      int [] wordCursor = new int [wordCount];
      int [] wordCursorMaxValue =  new int [wordCount];
                  
      for(int i=0;i<wordCount;i++)
      {
            wordCursor[i] = 0;
            ArrayList thisList = (ArrayList)WordLists[i];
            wordCursorMaxValue[i] = thisList.Count-1;
      }
                  
      bool loop = true;
      while(loop)
      {
            string phrase = null;
            for(int iWord=0;iWord<wordCount;iWord++)
            {
                  ArrayList thisList = (ArrayList)WordLists[iWord];
                  string thisword = thisList[wordCursor[iWord]].ToString();
                  phrase += thisword + " ";
            }
            ret.Add( phrase.Trim() );
                        
            for(int iCursor=lastWord;iCursor>=0;iCursor--)
            {
                  if(iCursor==lastWord)
                        wordCursor[iCursor]++;
                  if(wordCursor[iCursor]>wordCursorMaxValue[iCursor])
                  {
                        wordCursor[iCursor]=0;
                        if(iCursor==0)
                              loop = false;
                        else
                              wordCursor[iCursor-1]++;
                  }
            }
      }

      return ret;
}
0
 
LVL 3

Author Comment

by:mmiika
ID: 10804386
I wanted to loop through unknown number of arrays...
0
Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

 
LVL 12

Accepted Solution

by:
monosodiumg earned 50 total points
ID: 10805587
mmiika,

>The number of items in any array will be 1..n and number of arrays 1..n
You mean 1..n and 1..*m* or do you really mean that the number of items in each array is the same as the number of arrays?

A recursive version can be much tidier (this is air-code. Probably some syntax errors):
ArrayList function CrossProduct(ArrayList WordLists, string sRoot) {
      ArrayList OutList = new ArrayList();
      ArrayList Words = (ArrayList)WordLists[0];

      if (WordLists.Count == 1) {
            //Have reached last one so do not recurse.
                        
            foreach (Object  Word in Words) {
                  Outlist.Add sRoot + " " + (String)Word.trim();
            }
      } else {
            foreach (Object  Word in Words) {
                  Outlist.AddRange(CrossProduct(WordLists.GetRange(1,WordLists.Count - 1), sRoot + " " + (String)Word.trim();));
            }
      }
    return OutList ;
}

You call it with an empty string for the sRoot argument.

mono
0
 
LVL 20

Expert Comment

by:TheAvenger
ID: 10811104
When you want to loop through an unknown number of arrays, use StringCollection instead of array of strings and ArrayList instead of arrays. So you will have an ArrayList with StringCollections inside it, each StringCollection containing strings. Thus you can dynamically add strings and arrays and easily loop over them using the Count properties.
0
 
LVL 3

Author Comment

by:mmiika
ID: 11029045
monosodiumg, B-E-A-utiful, thanks...

Small modifications (a working function)

private ArrayList CrossProduct(ArrayList WordLists, string sRoot)
{
      ArrayList OutList = new ArrayList();
      ArrayList Words = (ArrayList)WordLists[0];

      if (WordLists.Count == 1)
      {
            //Have reached last one so do not recurse.
              foreach (Object  Word in Words)
                     OutList.Add(sRoot + " " + Word.ToString().Trim());
      }
      else
      {
            foreach (Object  Word in Words)
                  OutList.AddRange(CrossProduct(WordLists.GetRange(1,WordLists.Count - 1), sRoot + " " + Word.ToString().Trim()));
      }
      return OutList;
}
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: Najam
Having new technologies does not mean they will completely replace old components.  Recently I had to create WCF that will be called by VB6 component.  Here I will describe what steps one should follow while doing so, please feel free to post any qu…
The article shows the basic steps of integrating an HTML theme template into an ASP.NET MVC project
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question