C # string split and combination

Question

I have a string containing 5 numbers such as

'1,4,14,32,47' 

I want to make from this line 5 lines of 4 numbers in each

like:

  '1,4,14,32' '1,4,14,47' '1,4,32,47' '1,14,32,47' '4,14,32,47' 

what is an easy / quick way to do it

Is this a way to convert this array to unset every time a complex process is executed and merged them back into a string?

Is there an easy way to do this?

thanks

Answer 1

How about something like

 string s = "1,4,14,32,47"; string r = String.Join(",", s.Split(',').Where((x, index) => index != 1).ToArray()); 

Answer 2

Using string.Split() , you can create an array of strings. Skip it, so in each iteration of the loop you indicate which element should be skipped (on the first pass, ignore the first element, on the second pass, ignore the second element).

Inside this loop, create a new array containing all the elements, but the one you want to skip, then use string.Join() to create each result.

Answer 3

Take a look:

http://msdn.microsoft.com/en-us/magazine/ee310028.aspx Here you will find an example in F # that will give the correct background in combinations and permutations (which is called what you need). There is also code, I think it’s easy to translate it to C #

Sample code in C # (text in Italian, but code in English)

Answer 4

For those who need a more general algorithm, this is what gives n subsets of m elements:

 private void GetPermutations() { int permutationLength = 4; string s = "1,4,14,32,47"; string[] subS = s.Split(','); int[] indexS = new int[permutationLength]; List<string> result = new List<string>(); IterateNextPerm(permutationLength, indexS, subS, result); // Result will hold all your genberated data. } private void IterateNextPerm(int permutationLength, int[] pIndexes, string[] subS, List<string> result) { int maxIndexValue = subS.Count() - 1; bool isCorrect = true; for (int index = 0; index < permutationLength - 1; index++) { if (pIndexes[index] >= pIndexes[index + 1]) { isCorrect = false; break; } } // Print result if correct if (isCorrect) { string strNewPermutation = string.Empty; for (int index = 0; index < permutationLength; index++) { strNewPermutation += subS[pIndexes[index]] + ","; } result.Add(strNewPermutation.TrimEnd(',')); } // Increase last index position pIndexes[permutationLength - 1]++; // Check and fix if it out of bounds if (pIndexes[permutationLength - 1] > maxIndexValue) { int? lastIndexIncreased = null; // Step backwards and increase indexes for (int index = permutationLength - 1; index > 0; index--) { if (pIndexes[index] > maxIndexValue) { pIndexes[index - 1]++; lastIndexIncreased = index - 1; } } // Normalize indexes array, to prevent unnecessary steps if (lastIndexIncreased != null) { for (int index = (int)lastIndexIncreased + 1; index <= permutationLength - 1; index++) { if (pIndexes[index - 1] + 1 <= maxIndexValue) { pIndexes[index] = pIndexes[index - 1] + 1; } else { pIndexes[index] = maxIndexValue; } } } } if (pIndexes[0] < maxIndexValue) { IterateNextPerm(permutationLength, pIndexes, subS, result); } } 

I know that this is not the most pleasant encoding, but I wrote it right now in the last half hour, so I'm sure that there is something there that could be developed there.

Have fun coding!

Answer 5

 var elements = string.Split(','); var result = Enumerable.Range(0,elements.Length) .Reverse() .Select( i=> string.Join("," Enumerable.Range(0,i).Concat(Enumerable.Range(i+1,elements.Length - i - 1)) .Select(j=>elements[j]).ToArray() // This .ToArray() is not needed in NET 4 ) ).ToArray(); 

Answer 6

Your wording is rather confusing ... but the example is clear enough. just split by comma, then delete one index, then use string.Join (",", list); bring him back together.