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SequenceCompare - Comparing Sequences of IEnumerable

, 21 May 2009 Public Domain 12K 114 10
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A simple set of extension methods comparing sequences of IEnumerable
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Introduction

This short article describes a simple extension method for comparing sequences of values, and therefore sorting sequences against each other. 

The original need for these extension methods was that we were displaying a series of lists in grid cells, and we wanted to be able to sort the grid by that column. Ordinary alphabetical sorting on the display text was inadequate because if some elements were numbers, then alphabetical falls short of being useful. Using natural sorting on the display text was an option, but this was a simpler route.

What about Enumerable.SequenceEqual()?

While this code does resemble SequenceEqual, it's intended use is quite different. Since this provides comparison and not just equality, it enables you to sort sequences of sequences, rather than just testing if two sequencces are the same or not.

Using the Code

To use the code, simply include:

using SequenceCompareLib;

Or copy the code to your own project and modify the namespace.

After this, you can:

  • Call SequenceCompare<T> on any IEnumerable<T> where T implements IComparable<T>
  • Call List<IEnumerable<T>>.Sort() passing in SequenceComparer<T>.Default
  • Also specify your own IComparer<T> instance to do the element comparisons

For example:

var random = new Random();
var values = new List<IEnumerable<int>>();

for (int i = 0; i < 10; ++i)
{
  var items = new List<int>();
  var count = random.Next(0, 6);
  for (int j = 0; j < count; ++j)
  {
    items.Add(random.Next(5));
  }

  items.Sort();
  values.Add(items);
}

values.Sort(SequenceComparer<int>.Default);

This will produce something like this:

0 
0 1 
1 1 2 2 3 
1 2 
1 2 
1 3 
1 3 
3 
3 3 

History

  • 21st May, 2009: Initial post

License

This article, along with any associated source code and files, is licensed under A Public Domain dedication

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About the Author

Phil Martin
Software Developer (Senior) BitPlex Pty Ltd
Australia Australia
A professional developer in the Mining sector since 2000, Phil has a passion for creating robust, quality scientific applications.

I have started a software company, BitPlex, and I am focused on created a new and unique small business project planning tool called GamePlan.

My major fields of interest in software are 3D applications, visualisation, scheduling and optimisation, and novel UI design. My goal as a professional developer is to help people solve real world problems through reliable and fun to use software.

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Comments and Discussions

 
GeneralMust implement call IDisposable.Dispose on enumerators. Pin
Marc Brooks26-May-09 13:13
memberMarc Brooks26-May-09 13:13 
GeneralRe: Must implement call IDisposable.Dispose on enumerators. Pin
Phil Martin...26-May-09 16:24
memberPhil Martin...26-May-09 16:24 

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