Linq – Group and count items

linq

I have a .csv file (words.csv) containing 5000 words seperated by commas. Most of the strings are repeated values.

Can I use LINQ to do the following:

A. group common words together and show count of repeated words

so if apple has been repeated 5 times and banana 3 times..it should display as

apple – 5
banana – 3
and so on

B. Create another text file with duplicates removed.

Best Answer

Sure, here's the LINQ syntax in C#:

from word in words
group word into occurrences
select new
{
    Word = occurrences.Key,
    Count = occurrences.Count()
}

Or in "pure" C# method calls:

words.GroupBy(w => w)
     .Select(o => new 
                  { 
                     Word = o.Key,
                     Count = o.Count()
                  });

And to create a distinct list of words you just use the Distinct operator:

words.Distinct();

Related Solutions

.net – Which method performs better: .Any() vs .Count() > 0

If you are starting with something that has a .Length or .Count (such as ICollection<T>, IList<T>, List<T>, etc) - then this will be the fastest option, since it doesn't need to go through the GetEnumerator()/MoveNext()/Dispose() sequence required by Any() to check for a non-empty IEnumerable<T> sequence.

For just IEnumerable<T>, then Any() will generally be quicker, as it only has to look at one iteration. However, note that the LINQ-to-Objects implementation of Count() does check for ICollection<T> (using .Count as an optimisation) - so if your underlying data-source is directly a list/collection, there won't be a huge difference. Don't ask me why it doesn't use the non-generic ICollection...

Of course, if you have used LINQ to filter it etc (Where etc), you will have an iterator-block based sequence, and so this ICollection<T> optimisation is useless.

In general with IEnumerable<T> : stick with Any() ;-p

C# – LINQ – Left Join, Group By, and Count

from p in context.ParentTable
join c in context.ChildTable on p.ParentId equals c.ChildParentId into j1
from j2 in j1.DefaultIfEmpty()
group j2 by p.ParentId into grouped
select new { ParentId = grouped.Key, Count = grouped.Count(t=>t.ChildId != null) }

Best Answer

Related Solutions

.net – Which method performs better: .Any() vs .Count() > 0

C# – LINQ – Left Join, Group By, and Count

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