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Asked: 2020-08-15 09:03:44 +0800 CST 2020-08-15 09:03:44 +0800 CST

Find up to n Duplicates in Dictionary

  • 772

We have the following dictionary...

    Dictionary <int,string> dCits = new Dictionary<int, string>();
    dCits.Add(1,"London");
    dCits.Add(2, "London");
    dCits.Add(3, "Paris");
    dCits.Add(4, "Berlin");
    dCits.Add(5, "Paris");
    dCits.Add(6, "Madrid");
    dCits.Add(7, "Berlin");
    dCits.Add(8, "Madrid");
    dCits.Add(9, "Madrid");
    dCits.Add(10, "Atenas");
    dCits.Add(16, "London");
    dCits.Add(62, "Paris");
    dCits.Add(63, "Roma");

the idea is to take the cities that are only repeated N times if N is 2 London will be taken one and up to 2 times, or if N is 3 take the three london or 3 madrid including those of 2 and 1. if only 1 is required I mean N=1 would be like a Distinct... (as I indicate in the code below) the problem is when there are more than 1 that the distinct does not look good

foreach(var value in dCits.Values.Distinct())
{
  // aca indicar cuantas veces se necesitan dependiendo de N. 
 }

any ideas, be it with linq, a select or another command to solve this?

UPDATE The result of the new dictionary would be something like this:

if N=2

1,"London"
2, "London"
3, "Paris"
4, "Berlin"
5, "Paris"
6, "Madrid"
7, "Berlin"
8, "Madrid"
10, "Atenas"
63, "Roma"

if only at least 2 repeated are required and also selecting those that have one. for example rome

c#

2 Answers

  1. Best Answer

    We group by the values, and apply it to a new dictionary that has the city as key and the value count as value... and then with a where, we filter the list

    Dictionary <int,string> dCits = new Dictionary<int, string>();
dCits.Add(1,"London");
dCits.Add(2, "London");
dCits.Add(3, "Paris");
dCits.Add(4, "Belin");
dCits.Add(5, "Paris");
dCits.Add(6, "Madrid");
dCits.Add(7, "Berlin");
dCits.Add(8, "Madrid");
dCits.Add(9, "Madrid");
dCits.Add(10, "Atenas");
dCits.Add(16, "London");
dCits.Add(62, "Paris");
dCits.Add(63, "Roma");
int n = 3;
var v = dCits.GroupBy(o => o.Value)
    .ToDictionary(k => k.Key, g => g.Count())
    .Where(o => o.Value <= n);
var nuevo = dCits.Where(o => v.contains(o.value));

    and you would have the keys that you want in new

    • 1

  2. You can use GroupByto group the values ​​and apply anyfor only those that are repeated greater than 1.

    Example:

    var duplicates = dCits.GroupBy(x => x.Value).Any(g => g.Count() <=numero||(g.Count()==3||g.Count()==4));
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