C
C#•5mo ago
Evyr

✅ Struggling to use custom comparer with a list of KeyValuePairs

I'm trying to sort a list of keyvaluepairs on the key. I've defined an IComparer using Comparer.Create, but the list after sorting is identical to before. I can't use a SortedList because that requires unique keys. 
IComparer<KeyValuePair<float, int>> comp = Comparer<KeyValuePair<float, int>>.Create((a, b) => a.Key < b.Key ? 1 : 0);
List<KeyValuePair<float, int>> li = [
    new(1f, 1),
    new(1.5f, 2),
    new(2.5f, 3),
    new(0.5f, 4),
    new(0.2f, 5)
    ];
li.Sort(comp);

foreach (var kvp in li)
    Console.WriteLine(kvp.Key + ", " + kvp.Value);
IComparer<KeyValuePair<float, int>> comp = Comparer<KeyValuePair<float, int>>.Create((a, b) => a.Key < b.Key ? 1 : 0);
List<KeyValuePair<float, int>> li = [
    new(1f, 1),
    new(1.5f, 2),
    new(2.5f, 3),
    new(0.5f, 4),
    new(0.2f, 5)
    ];
li.Sort(comp);

foreach (var kvp in li)
    Console.WriteLine(kvp.Key + ", " + kvp.Value);
The output looks like 
1, 1
1.5, 2
2.5, 3
0.5, 4
0.2, 5
1, 1
1.5, 2
2.5, 3
0.5, 4
0.2, 5
Whereas I'd expect it to be sorted in either ascending or descending order.
5 Replies
Angius
Angius•5mo ago
You could just OrderBy() it
MODiX
MODiX•5mo ago
Angius
REPL Result: Success
List<KeyValuePair<float, int>> li = [
    new(1f, 1),
    new(1.5f, 2),
    new(2.5f, 3),
    new(0.5f, 4),
    new(0.2f, 5)
    ];
li.OrderBy(kv => kv.Key)
List<KeyValuePair<float, int>> li = [
    new(1f, 1),
    new(1.5f, 2),
    new(2.5f, 3),
    new(0.5f, 4),
    new(0.2f, 5)
    ];
li.OrderBy(kv => kv.Key)
Result: OrderedEnumerable<KeyValuePair<float, int>, float>
[
  {
    "key": 0.2,
    "value": 5
  },
  {
    "key": 0.5,
    "value": 4
  },
  {
    "key": 1,
    "value": 1
  },
  {
    "key": 1.5,
    "value": 2
  },
  {
    "key": 2.5,
    "value": 3
  }
]
[
  {
    "key": 0.2,
    "value": 5
  },
  {
    "key": 0.5,
    "value": 4
  },
  {
    "key": 1,
    "value": 1
  },
  {
    "key": 1.5,
    "value": 2
  },
  {
    "key": 2.5,
    "value": 3
  }
]
Compile: 414.906ms | Execution: 56.561ms | React with ❌ to remove this embed.
Evyr
EvyrOP•5mo ago
Thank you
cap5lut
cap5lut•5mo ago
btw, a.Key < b.Key ? 1 : 0 is seems to be wrong. a negative value idicates that a is smaller, zero indicates that they are equal, and a positive value indicates that a is bigger.
Evyr
EvyrOP•5mo ago
ah, thanks just tried both of those and they both work, thank you both

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