How do I print the mobile names in the ascending order whose prices are same?

Question

1.00/5 (2 votes)

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List<Mobiles> mobiles = new List<Mobiles>()
            {
                new Mobiles { MobileID = 1, MobileName = "Samsung S21", Price = 19000, Network = "4G" },
                new Mobiles { MobileID = 3, MobileName = "Nokia C2", Price = 19000, Network = "4G" },
                new Mobiles { MobileID = 2, MobileName = "Motorola G40", Price = 29000, Network = "5G" },
                new Mobiles { MobileID = 4, MobileName = "Samsung A24", Price = 99000, Network = "4G" },
                new Mobiles { MobileID = 7, MobileName = "Samsung S33", Price = 89000, Network = "4G" },
                new Mobiles { MobileID = 6, MobileName = "Realme XT", Price = 77000, Network = "5G" },
                new Mobiles { MobileID = 8, MobileName = "Realme Narzo", Price = 67000, Network = "5G" },
                new Mobiles { MobileID = 11, MobileName = "Vivo V17", Price = 77000, Network = "4G" }
            };

What I have tried:

mobiles.GroupBy(x => x.Price)
                .Select(x => new
                {
                    Name = x.Key
                    ,
                    Price = x.Count()
                })
                .Where(x => x.Price > 1)
                .ToList().ForEach(x => Console.WriteLine(x.Name+" "+x.Price));

In the foreach section I am unable to access the MobileName field. Please help?

Posted 9-Aug-23 1:30am

Samriddha Chowdhury

Updated 9-Aug-23 2:03am

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3 solutions

Solution 2

See the example at Enumerable.GroupBy Method (System.Linq) | Microsoft Learn[^].

Posted 9-Aug-23 1:50am

Richard MacCutchan

Solution 1

You don't include it in the Select - just Name and Price so you can't access it in the results: it doesn't exist in the new anonymous type you created.

And you can't add it to the type directly because the Group contains multiple entries for the Mobile name!
What you need is to create a Dictionary of sublists, which can take a bit of getting your head round - it took me a while when I needed to do just that. So I wrote a quick tip on how to do it: Using Linq to create a Dictionary of sub-Lists by grouping from a collection.[^]

Posted 9-Aug-23 1:38am

OriginalGriff

Updated 9-Aug-23 1:39am

v2

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Richard Deeming · Accepted Answer · 2023-08-09T02:03:00

Solution 3

Try:

C#

var groupedMobiles = mobiles.GroupBy(m => m.Price, (key, items) => new
{
    Price = key,
    Items = items.OrderBy(m => m.MobileName).ToList(),
});

foreach (var group in groupedMobiles)
{
    Console.WriteLine("Price: {0}", group.Price);
    foreach (Mobiles mobile in group.Items)
    {
        Console.WriteLine("* {0} ({1})", mobile.MobileName, mobile.Network);
    }
    Console.WriteLine();
}

Posted 9-Aug-23 2:03am

Richard Deeming

Comments

George Swan 9-Aug-23 10:24am

An excellent solution. Could I suggest that the ToList method call is not needed and can be omitted?

Samriddha Chowdhury 10-Aug-23 2:13am

Hi could you please explain what this piece of code is doing?

(key, items) => new
{
Price = key,
Items = items.OrderBy(m => m.MobileName).ToList(),
});

Richard Deeming 10-Aug-23 3:45am

That's a lambda expression used as the resultSelector parameter of the GroupBy method:
Enumerable.GroupBy Method (System.Linq) | Microsoft Learn[^]

For each group of items, it is passed the key of the group and the list of items in that group. It then maps those to an anonymous object which is the type of item in the returned sequence.

The alternative would be to group and then select:

mobiles.GroupBy(m => m.Price).Select(group => new
{
    Price = group.Key,
    Items = group.OrderBy(m => m.MobileName).ToList(),
});

Samriddha Chowdhury 11-Aug-23 7:40am

thank you so much. this one is easier for me