Agfdhyk

I just started learning lambda/linq. Here's what I have so far.

var frequency = from f in "trreill".ToList()

                group f by f into letterfrequency

                select letterfrequency;



foreach (var f in frequency)

{

    Console.WriteLine($"{f.Key}{f.Count()}");

}

Here is the output:

t1 r2 e1 i1 l2

Output needed:

e1i1l2r2t1

Can't figure out how to sort properly. Any thoughts to what I'm doing wrong?

The thing you're missing is adding an orderby to your LINQ statement:

var frequency = from f in "trreill"

                group f by f into letterfrequency

                orderby letterfrequency.Key

                select new

                {

                    Letter = letterfrequency.Key,

                    Frequency = letterfrequency.Count()

                };



foreach (var f in frequency)

{

    Console.WriteLine($"{f.Letter}{f.Frequency}");

}

The letterfrequency has a property called Key which contains the letter for each group, so adding orderby letterfrequency.Key sorts the results to give you the output you're after:

e1

i1

l2

r2

t1

I've also tweaked the result of the query slightly (simply to show that it's something that's possible) to generate a new anonymous type that contains the Letter and the Frequency as named properties. This makes the code in the Console.WriteLine a littl clearer as the properties being used are called Letter and Frequency rather than Key and the Count() method.

Turning it up to 11, using C# 7.0 Tuples

If you're using C# 7.0, you could replace the use of an anonymous type with Tuples, that means that the code would now look like this:

var frequency = from f in "trreill"

                group f by f into letterfrequency

                orderby letterfrequency.Key

                select

                (

                    Letter: letterfrequency.Key,

                    Frequency: letterfrequency.Count()

                );





foreach (var (Letter, Frequency) in frequency)

{

    Console.WriteLine($"{Letter}{Frequency}");

}

I've blogged about this, and there are plenty of other resources that describe them, including this Stackoverflow question that asks 'Are C# anonymous types redundant in C# 7', if you want a deeper dive into Tuples, what they are, how they work and why/when you might want to use them in preference to anonymous types.

Just sort your list as following:

        foreach (var f in frequency.OrderBy(item=>item.Key))

        {

            Console.WriteLine($"{f.Key}{f.Count()}");

        }

I would select into an anonymous object:

var frequency = from f in "trreill"

                     group f by f into letterfrequency

                     select new { Key = letterfrequency.Key, Count = letterfrequency.Count() };

Then I would order it like so:

foreach (var f in frequency.OrderBy(x => x.Key))

{

    Console.WriteLine($"{f.Key}{f.Count}");

}