Question

Can anyone please help me sort the following List of Strings:

The List<String> contains coordinates

[0] “0 0”
[1] “0 1”
[2] “0 2”
[3] “0 3”
[4] “1 1”
[5] “1 2”
[6] “1 3”

Although It may not always be in that order I would like to make sure it is, by sorting / ordering it (sort by X coordinate ASC then by Y coordinate ASC)

I have tried this but it does not alter the list at all? – see below

boardObjectList.OrderBy(p => (p.Split())[0]).ThenBy(p=> (p.Split())[1]);

Any ideas?

Thanks,
JP

Answer 1

OrderBy and ThenBy do not modify the original list, they only return a new list (in the form of an IEnumerable<>). What you need to do is create a new List<> from the resulting IEnumerable<>, like this:

// Note that we are assigning the variable to a new list
boardObjectList = boardObjectList.OrderBy(p => (p.Split())[0])
                                 .ThenBy(p => (p.Split())[1])
                                 .ToList(); // Also note that we call ToList,
                                            // to get a List from an IEnumerable

You will get strange results when storing numbers in strings, and trying to sort. I recommend changing your code to this:

boardObjectList = boardObjectList.OrderBy(p => int.Parse(p.Split()[0]))
                                 .ThenBy(p => int.Parse(p.Split()[1]))
                                 .ToList();

This method converts the strings into integers before sorting. The reason to do this is that string sorting sorts alphabetically, leading to sorting like this:

1
10
11
12
2
3
4
5
6
7
8
9