I needed to group the same dataset into several groups. So, instead of repeatedly querying the dataset, I've created an extension capable of doing it once. The caveat is that the result is materialized in dictionaries, because I have not managed to find a way to avoid that. Maybe you can?
public static IDictionary <string, Dictionary <object, HashSet>> MultiGroupPar(this IEnumerable source, params (string Label, Func getter)[] groupers)
{
if (source == null) throws a new argument ArgumentNullException (nameof (source));
if (groupers == null) throws a new argument ArgumentNullException (nameof (groupers));
IDictionary <string, Dictionary <object, HashSet>> results = new Dictionary <string, Dictionary <object, HashSet>> ();
using (var enumer = source.GetEnumerator ())
{
while (enumer.MoveNext ())
{
foreach (var label, var func) in grouper)
{
if (! results.TryGetValue (label, as dictation))
{
dict = new Dictionary <object, HashSet> ();
results[label] = dict;
}
var key = func (enumer.Current);
if (! dict.TryGetValue (key, out var set))
{
set = new HashSet();
dict[key] = together;
}
set.Add (enumer.Current);
}
}
}
return the results;
}
Use case:
static empty TestMultiGrouping ()
{
chain[] data =
{
"Black",
"White",
"Yellow",
"green",
"Red",
"blue",
"Cyan"
"Magenta",
"Orange"
};
foreach (result var in data.MultiGroupBy (
("First UCase", s => s.Length> 0 && char.IsUpper (s[0])),
("Length", s => s.Length),
("Length four", s => s.Length == 4),
("Contains & # 39;"), s => s.Contains (& # 39; e),
("Num n", s => s.Count (c => c == n))))
{
Console.WriteLine ($ "Results for {result.Key}:");
foreach (var dict in result.Value)
{
Console.WriteLine ($ "{dict.Key}: {dict.Value.Count} [{(string.Join(", ", dict.Value))}]");
}
Console.WriteLine ();
}
}
