Is there a way that I could return duplicate values from an array in C#? also im looking to write a small algorithm that would return the most number of duplicate values in an array. for example
[1, 2,2,2 3,3] I need to return the duplicate values with the most number of occurrences and the number of occurrences as well.
I think I saw some post which said that It could be done using Linq but I have no clue what Linq is
Any help would be much appreciated.
Try this:
int[] data = new int[] { 1, 2, 2, 2, 3, 3 };
IGrouping<int, int> mostOccurrences = data
.GroupBy(value => value)
.OrderByDescending(group => group.Count())
.First();
Console.WriteLine("Value {0} occurred {1} time(s).", mostOccurrences.Key, mostOccurrences.Count());
Note that if multiple values occur the same number of times (such as if you added another 3 to that list), the above code will only list one of them. To handle that situation, try this:
int[] data = new int[] { 1, 2, 2, 2, 3, 3, 3 };
var occurrenceInfos = data
.GroupBy(value => value)
.Select(group =>
new {
Count = group.Count(),
Value = group.Key
}
);
int maxOccurrenceCount = occurrenceInfos.Max(info => info.Count);
IEnumerable<int> maxOccurrenceValues = occurrenceInfos
.Where(info => info.Count == maxOccurrenceCount)
.Select(info => info.Value);
foreach (int value in maxOccurrenceValues)
Console.WriteLine("Value {0} occurred {1} time(s).", value, maxOccurrenceCount);
maxOccurrenceValues for, but since it's of type IEnumerable<int> you can use it as-is, or if you need an array call maxOccurrenceValues.ToArray().Here's my take on this:
var data = new[] { 1, 2, 2, 2, 3, 3, };
var occurences =
data
.ToLookup(x => x)
.ToDictionary(x => x.Key, x => x.Count());
var mostOccurences =
occurences
.OrderByDescending(x => x.Value)
.First();
These will give you the following results:
var occurences = from d in data.ToLookup(x => x) select new { d.Key, Count = d.Count() };