C# Order List of Strings by value

Question

I have a List:

List<string> allValues = new List<string>();

It may contain values like this:

-3,003-m

2,086

-1, 006-mx

etc.

I sorted it with this:

allValues = allValues.OrderBy(q => q).ToList<string>();
allValues.Reverse();

The problem is, that it somehow does not differ between normal values and negative ones (I'd expect that to work even if they are strings).

So instead of:

3,001 | 3,003-m | 2,086 | 2,145-m | 1,004 | 0,033 | -1,008-m | -2,490

it looks like this:

3,001 | 3,003-m | 2,086 | -2,490 | 2,145-m | -1,008-m | 1,004 | 0,033

If now negative or positive, it seems to treat them as the same, resulting in a somewhat random sorted List.

I am aware that there might be better approaches to this, but I wanted to know if it is possible to resolve this in this specific scenario.

String ordering and int/decimal ordering are two different things. — mybirthname
– mybirthname, Commented Jan 25, 2016 at 10:22
Do you want the result to be greater to smaller? then shouldn't the expected result be: 3,003-m | 3,001 | 2,145-m | 2,086 | 1,004 | 0,033 | -1,008-m | -2,490 ? — Ian
– Ian, Commented Jan 25, 2016 at 10:32

MakePeaceGreatAgain · Accepted Answer · 2016-01-25 10:32:11Z

2

As allValues is a list of strings also the rules for sorting strings apply for sorting. As you need numerical rules of sorting you have to convert the elements to numbers before sorting, e.g. by calling Convert.ToInt32).

So your ordering looks like this:

var result = allValues.OrderBy(q => 
    Convert.ToInt32(q.SubString(0, q.IndexOf(","))))
    .ToList<string>();

Which will perform on only extracting the numeric part and order by it, however it retains the actual strings.

edited Jan 25, 2016 at 10:32

answered Jan 25, 2016 at 10:23

MakePeaceGreatAgain

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3 Comments

mybirthname Over a year ago

This is a comment ... Calling Convert.ToInt32 on -1,008-m will throw an exception.

Kohnarik Over a year ago

The problem is the -m / -mx part. I need them in my values, but because of that, I can't convert them to int.

Kohnarik Over a year ago

I don't know if someone ever told you this, but you're a genius. Thanks alot!

Ian · Accepted Answer · 2016-01-25 10:30:27Z

1

This should do the job:

var result = (from s in allValues
             let val = s.Split(new string[] { "-m" }, StringSplitOptions.RemoveEmptyEntries)[0]
             let val2 = double.Parse(val)
             orderby val2
             select s).Reverse();

The idea is to get the first element divided by "-m", you can simply add the split option with something else ("-mx", "-p", etc) as per necessary.

edited Jan 25, 2016 at 10:30

answered Jan 25, 2016 at 10:27

Ian

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3 Comments

mybirthname Over a year ago

There is string -mx too in the example, I will suppose there will be more from this.

Kohnarik Over a year ago

Yeah, there are multiple possible endings (like -mx or -d), but nonetheless thank you for this idea.

Kohnarik Over a year ago

@Ian I didn't say it didn't work. It does indeed work.^^

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