Question

Note: This is part 1 of a 2 part question.

Part 2 here

I’m wanting to more about sorting algorithms and what better way to do than then to code! So I figure I need some data to work with.

My approach to creating some “standard” data will be as follows: create a set number of items, not sure how large to make it but I want to have fun and make my computer groan a little bit 😀

Once I have that list, I’ll push it into a text file and just read off that to run my algorithms against. I should have a total of 4 text files filled with the same data but just sorted differently to run my algorithms against (see below).

Correct me if I’m wrong but I believe I need 4 different types of scenarios to profile my algorithms.

• Randomly sorted data (for this I’m going to use the knuth shuffle)
• Reversed data (easy enough)
• Nearly sorted (not sure how to implement this)
• Few unique (once again not sure how to approach this)

This question is for generating a nearly sorted list.

Which approach is best to generate a nearly sorted list on predefined data?

Answer 1

Answering my own question here. All this does is taking a sorted list and shuffling up small sections of it.

    public static T[] ShuffleBagSort<T>(T[] array, int shuffleSize)
    {
        Random r = _random;
        for (int i = 0; i < array.Length; i += shuffleSize)
        {
            //Prevents us from getting index out of bounds, while still getting a shuffle of the 
            //last set of un shuffled array, but breaks for loop if the number of unshuffled array is 1
            if (i + shuffleSize > array.Length)
            {
                shuffleSize = array.Length - i;

                if (shuffleSize <= 1) // should never be less than 1, don't think that's possible lol
                    continue;
            }

            if (i % shuffleSize == 0)
            {
                for (int j = i; j < i + shuffleSize; j++)
                {
                    // Pick random element to swap from our small section of the array.
                    int k = r.Next(i, i + shuffleSize);
                    // Swap.
                    T tmp = array[k];
                    array[k] = array[j];
                    array[j] = tmp;
                }
            }
        }

        return array;
    }