Dotnet-StuffWorld

Some Common Operations using LINQ To XML - Part I

Some Common Operations using LINQ To XML - Part II

Some Common Operations using LINQ To XML - Part III

Query NonGeneric Types using LINQ in C# and VB.NET

Fun with LINQ - Find the Longest and Shortest Type Name in .NET 3.5 using LINQ :
While browsing through the forums a couple of days ago, I came across this query where the user wanted to list down the types in .NET 3.5 in the order of the length of their names. He also wanted to find out the total number of types in .NET 3.5 and 2.0. Here’s my attempt of how to do so using LINQ. If you know of a better way or find any discrepancy in the results displayed, please do let me know.
I have created a Console Application in Visual Studio 2008. Let’s take the problem one at a time.
Before I begin, here’s a disclaimer. The results may vary on your machine. Since we are referring to the GetExportedTypes() which returns type visible outside the assembly, you can get different results by adding new references (Right click project > Add Reference ) or by changing the access modifiers of the types. Having said that, let’s get started:

Listing down the public types in .NET 3.5:
We can use reflection and a simple LINQ query to get the Types in .NET 3.5 as shown below:
C#
static void Main(string[] args)
{
var assemb = from assembly in AppDomain.CurrentDomain.GetAssemblies()
from aType in assembly.GetExportedTypes()
select aType;

var aList = assemb
.Where(x => x.Assembly.FullName.Contains("Version=3.5.0.0"))

foreach (var a in aList)
{
Console.WriteLine("{0}", a.Name);
}

Console.ReadLine();
}
VB.NET
Sub Main()
Dim assemb = _
From assembly In AppDomain.CurrentDomain.GetAssemblies(),aType In assembly.GetExportedTypes() _
Select aType

Dim aList = assemb.Where(Function(x) x.Assembly.FullName.Contains("Version=3.5.0.0"))
For Each a In aList
Console.WriteLine("{0}", a.Name)
Next

Console.ReadLine()
End Sub
Note: If you want to Fully qualify the type name, use v.FullName instead of v.Name

Listing down the types in the order of the length of their names:
An OrderBy Descending would do the trick here as shown below:
C#
static void Main(string[] args)
{
var assemb = from assembly in AppDomain.CurrentDomain.GetAssemblies()
from aType in assembly.GetExportedTypes()
select aType;

var aList = assemb
.Where(x => x.Assembly.FullName.Contains("Version=3.5.0.0"))
.OrderByDescending(x => x.Name.Length);

foreach (var a in aList)
{
Console.WriteLine("Length: {0} {1}", a.Name.Length, a.Name);
}

Console.ReadLine();
}

VB.NET
Sub Main(ByVal args() As String)
Dim assemb = _
From assembly In AppDomain.CurrentDomain.GetAssemblies(),aType In assembly.GetExportedTypes() _
Select aType

Dim aList = assemb.Where(Function(x) x.Assembly.FullName.Contains("Version=3.5.0.0")).OrderByDescending(Function(x) x.Name.Length)

For Each a In aList
Console.WriteLine("Length: {0} {1}", a.Name.Length, a.Name)
Next a

Console.ReadLine()
End Sub

Total types in .NET 2.0 and .NET 3.5:
In order to find the total types in .NET 2.0 and .NET 3.5, we will use the GroupBy clause as shown here:
C#
static void Main(string[] args)
{
var assemb = from assembly in AppDomain.CurrentDomain.GetAssemblies()
from aType in assembly.GetExportedTypes()
select aType;


var vers = assemb.Select(
m => m.Assembly.FullName.Split(",".ToCharArray())[1])
.GroupBy(x => x)
.Select(x => new { VerName = x.Key, Count = x.Count() });

foreach (var ver in vers)
{
Console.WriteLine(".NET {0} has {1} types\n",ver.VerName, ver.Count);
}


Console.ReadLine();
}



VB.NET

Sub Main(ByVal args() As String)
Dim assemb = _
From assembly In AppDomain.CurrentDomain.GetAssemblies(), aType In assembly.GetExportedTypes() _
Select aType


Dim vers = assemb.Select(Function(m) m.Assembly.FullName.Split(",".ToCharArray())(1)) _
.GroupBy(Function(x) x) _
.Select(Function(x) New With {Key .VerName = x.Key, Key .Count = x.Count()})

For Each ver In vers
Console.WriteLine(".NET {0} has {1} types" & Constants.vbLf, ver.VerName, ver.Count)
Next ver


Console.ReadLine()
End Sub


http://www.dotnetcurry.com/ShowArticle.aspx?ID=272

Well I hope you got a fair bit of idea of the power of a GroupBy in LINQ and so did Linda, our fictional HR J. So Happy LINQing and keep practising! I hope you liked the article and I thank you for viewing it. The entire source code of this article in C# and VB.NET can be downloaded over here

4. Total No. Of Birthdays each Year: [part5]
To get a total of the employees born in the same year, use this query
C#
// Count people grouped by the Year in which they were born
var grpCountYrMon = empList.GroupBy(employees => employees.DOB.Year)
.Select(lst => new {Year = lst.Key, Count = lst.Count()} );

foreach (var employee in grpCountYrMon)
{
Console.WriteLine("\n{0} were born in {1}", employee.Count, employee.Year);
}
Console.ReadLine();
VB.NET
' Count people grouped by the Year in which they were born
Dim grpCountYrMon = empList.GroupBy(Function(employees) employees.DOB.Year).Select(Function(lst) New With {Key .Year = lst.Key, Key .Count = lst.Count()})

For Each employee In grpCountYrMon
Console.WriteLine(Constants.vbLf & "{0} were born in {1}", employee.Count, employee.Year)
Next employee
Console.ReadLine()

5. Sex Ratio
To find the sex ratio in the company, use this query
C#
// Sex Ratio
var ratioSex = empList.GroupBy(ra => ra.Sex)
.Select( emp => new
{
Sex = emp.Key,
Ratio = (emp.Count() * 100) / empList.Count
});

foreach (var ratio in ratioSex)
{
Console.WriteLine("\n{0} are {1}%", ratio.Sex, ratio.Ratio);
}
Console.ReadLine();
VB.NET ' Sex Ratio
Dim ratioSex = empList.GroupBy(Function(ra) ra.Sex).Select(Function(emp) New With {Key .Sex = emp.Key, Key .Ratio = (emp.Count() * 100) / empList.Count})

For Each ratio In ratioSex
Console.WriteLine(Constants.vbLf & "{0} are {1}%", ratio.Sex, ratio.Ratio)
Next ratio
Console.ReadLine()



finish..,

3. List of employees grouped by the Year and Month in which they were born: [part4]
In order to group the employees based on the year and then the month in which they were born, use this query
C#
// Group people by the Year and Month in which they were born
var grpOrderedYrMon = empList.GroupBy(employees =>
new DateTime(employees.DOB.Year, employees.DOB.Month, 1)).OrderBy(employees => employees.Key); ;

foreach (var employee in grpOrderedYrMon)
{
Console.WriteLine("\nEmployees Born in Year {0} - Month {1} is/are :", employee.Key.Year, employee.Key.Month);
foreach (var empl in employee)
{
Console.WriteLine("{0}: {1}", empl.ID, empl.FName);
}
}
Console.ReadLine();
VB.NET
' Group people by the Year and Month in which they were born
Dim grpOrderedYrMon = empList.GroupBy(Function(employees) New DateTime(employees.DOB.Year, employees.DOB.Month, 1)).OrderBy(Function(employees) employees.Key)


For Each employee In grpOrderedYrMon
Console.WriteLine(Constants.vbLf & "Employees Born in Year {0} - Month {1} is/are :", employee.Key.Year, employee.Key.Month)
For Each empl In employee
Console.WriteLine("{0}: {1}", empl.ID, empl.FName)
Next empl
Next employee
Console.ReadLine()

Cont..,

2. List of Employees grouped by the Year in which they were Born : [part3]
In order to group the employees based on the year in which they were born, use this query
C#
// Group People by the Year in which they were born
var grpOrderedYr = empList.GroupBy(employees => employees.DOB.Year).OrderBy(employees => employees.Key);

foreach (var employee in grpOrderedYr)
{
Console.WriteLine("\nEmployees Born In the Year " + employee.Key);
foreach (var empl in employee)
{
Console.WriteLine("{0,2} {1,7}", empl.ID, empl.FName);
}
}
Console.ReadLine();
VB.NET
' Group People by the Year in which they were born
Dim grpOrderedYr = empList.GroupBy(Function(employees) employees.DOB.Year).OrderBy(Function(employees) employees.Key)

For Each employee In grpOrderedYr
Console.WriteLine(Constants.vbLf & "Employees Born In the Year " & employee.Key)
For Each empl In employee
Console.WriteLine("{0,2} {1,7}", empl.ID, empl.FName)
Next empl
Next employee
Console.ReadLine()

cont..,

1. List of Employees grouped by the first letter of their FirstName
To display a list of employees group by the first alphabet of their FirstName, use this query
C#
// Group People by the First Letter of their FirstName
var grpOrderedFirstLetter = empList.GroupBy(employees =>
new String(employees.FName[0], 1)).OrderBy(employees => employees.Key.ToString());;

foreach (var employee in grpOrderedFirstLetter)
{
Console.WriteLine("\n'Employees having First Letter {0}':", employee.Key.ToString());
foreach (var empl in employee)
{
Console.WriteLine(empl.FName);
}
}

Console.ReadLine();
VB.NET
' Group People by the First Letter of their FirstName
Dim grpOrderedFirstLetter = empList.GroupBy(Function(employees) New String(employees.FName(0), 1)).OrderBy(Function(employees) employees.Key.ToString())


For Each employee In grpOrderedFirstLetter
Console.WriteLine(Constants.vbLf & "'Employees having First Letter {0}':", employee.Key.ToString())
For Each empl In employee
Console.WriteLine(empl.FName)
Next empl
Next employee

Console.ReadLine()

cont..,

Some Common GroupBy Operations on List<> using LINQ:
The ‘GroupBy’ feature in LINQ is amazing and very powerful. When you use a ‘GroupBy’ in LINQ, internally it calls an extension method which returns a sequence of System.Collections.Generic.IEnumerable<(Of <(IGrouping<(Of <(TKey, TSource>)>)>)>)
The GroupBy<(Of <(TSource, TKey>)>)(IEnumerable<(Of <(TSource>)>), Func<(Of <(TSource, TKey>)>)) method returns a collection of IGrouping<(Of <(TKey, TElement>)>) objects, one for each distinct key that was encountered. The key represents the attribute that is common to each value in the IGrouping<(Of <(TKey, TElement>)>) and can be accessed using a ForEach loop.
In order to understand GroupBy in LINQ, let’s take an example. Linda is an HR in a small private firm. To facilitate the HR process, she wants a simple console application to obtain some quick results. She needs the following details of Employees:
- Raw List of Employees
- List of Employees grouped by the first letter of their FirstName
- List of employees grouped by the Year in which they were born
- List of employees grouped by the Year and Month in which they were born
- Total count of employees having Birthdays in the same Year
- Sex Ratio
Let’s take these requirements one by one and see how they can be easily achieved using the ‘GroupBy’ in LINQ. We will first create a simple list of employees (List) and add some data to it.
C#
class Program
{
static void Main(string[] args)
{
List empList = new List();
empList.Add(new Employee() { ID = 1, FName = "John", MName = "", LName = "Shields", DOB = DateTime.Parse("12/11/1971"), Sex = 'M' });
empList.Add(new Employee() { ID = 2, FName = "Mary", MName = "Matthew", LName = "Jacobs", DOB = DateTime.Parse("01/17/1961"), Sex = 'F' });
empList.Add(new Employee() { ID = 3, FName = "Amber", MName = "Carl", LName = "Agar", DOB = DateTime.Parse("12/23/1971"), Sex = 'M' });
empList.Add(new Employee() { ID = 4, FName = "Kathy", MName = "", LName = "Berry", DOB = DateTime.Parse("11/15/1976"), Sex = 'F' });
empList.Add(new Employee() { ID = 5, FName = "Lena", MName = "Ashco", LName = "Bilton", DOB = DateTime.Parse("05/11/1978"), Sex = 'F' });
empList.Add(new Employee() { ID = 6, FName = "Susanne", MName = "", LName = "Buck", DOB = DateTime.Parse("03/7/1965"), Sex = 'F' });
empList.Add(new Employee() { ID = 7, FName = "Jim", MName = "", LName = "Brown", DOB = DateTime.Parse("09/11/1972"), Sex = 'M' });
empList.Add(new Employee() { ID = 8, FName = "Jane", MName = "G", LName = "Hooks", DOB = DateTime.Parse("12/11/1972"), Sex = 'F' });
empList.Add(new Employee() { ID = 9, FName = "Robert", MName = "", LName = "", DOB = DateTime.Parse("06/28/1964"), Sex = 'M' });
empList.Add(new Employee() { ID = 10, FName = "Cindy", MName = "Preston", LName = "Fox", DOB = DateTime.Parse("01/11/1978"), Sex = 'M' });

// Printing the List
Console.WriteLine("\n{0,2} {1,7} {2,8} {3,8} {4,23} {5,3}",
"ID", "FName", "MName", "LName", "DOB", "Sex");
empList.ForEach(delegate(Employee e)
{
Console.WriteLine("{0,2} {1,7} {2,8} {3,8} {4,23} {5,3}",
e.ID, e.FName, e.MName, e.LName, e.DOB, e.Sex);
});

Console.ReadLine();

}

class Employee
{
public int ID { get; set; }
public string FName { get; set; }
public string MName { get; set; }
public string LName { get; set; }
public DateTime DOB { get; set; }
public char Sex { get; set; }
}


VB.NET
Module Module1

Sub Main()
Dim empList As New List(Of Employee)()
empList.Add(New Employee() With {.ID = 1, .FName = "John", .MName = "", .LName = "Shields", .DOB = DateTime.Parse("12/11/1971"), .Sex = "M"c})
empList.Add(New Employee() With {.ID = 2, .FName = "Mary", .MName = "Matthew", .LName = "Jacobs", .DOB = DateTime.Parse("01/17/1961"), .Sex = "F"c})
empList.Add(New Employee() With {.ID = 3, .FName = "Amber", .MName = "Carl", .LName = "Agar", .DOB = DateTime.Parse("12/23/1971"), .Sex = "M"c})
empList.Add(New Employee() With {.ID = 4, .FName = "Kathy", .MName = "", .LName = "Berry", .DOB = DateTime.Parse("11/15/1976"), .Sex = "F"c})
empList.Add(New Employee() With {.ID = 5, .FName = "Lena", .MName = "Ashco", .LName = "Bilton", .DOB = DateTime.Parse("05/11/1978"), .Sex = "F"c})
empList.Add(New Employee() With {.ID = 6, .FName = "Susanne", .MName = "", .LName = "Buck", .DOB = DateTime.Parse("03/7/1965"), .Sex = "F"c})
empList.Add(New Employee() With {.ID = 7, .FName = "Jim", .MName = "", .LName = "Brown", .DOB = DateTime.Parse("09/11/1972"), .Sex = "M"c})
empList.Add(New Employee() With {.ID = 8, .FName = "Jane", .MName = "G", .LName = "Hooks", .DOB = DateTime.Parse("12/11/1972"), .Sex = "F"c})
empList.Add(New Employee() With {.ID = 9, .FName = "Robert", .MName = "", .LName = "", .DOB = DateTime.Parse("06/28/1964"), .Sex = "M"c})
empList.Add(New Employee() With {.ID = 10, .FName = "Cindy", .MName = "Preston", .LName = "Fox", .DOB = DateTime.Parse("01/11/1978"), .Sex = "M"c})

' Printing the List
Console.WriteLine(Constants.vbLf & "{0,2} {1,7} {2,8} {3,8} {4,23} {5,3}", "ID", "FName", "MName", "LName", "DOB", "Sex")
empList.ForEach(AddressOf AnonymousMethod1)

Console.ReadLine()
End Sub

Private Sub AnonymousMethod1(ByVal e As Employee)
Console.WriteLine("{0,2} {1,7} {2,8} {3,8} {4,23} {5,3}", e.ID, e.FName, e.MName, e.LName, e.DOB, e.Sex)
End Sub

End Module

Friend Class Employee
Private privateID As Integer
Public Property ID() As Integer
Get
Return privateID
End Get
Set(ByVal value As Integer)
privateID = value
End Set
End Property
Private privateFName As String
Public Property FName() As String
Get
Return privateFName
End Get
Set(ByVal value As String)
privateFName = value
End Set
End Property
Private privateMName As String
Public Property MName() As String
Get
Return privateMName
End Get
Set(ByVal value As String)
privateMName = value
End Set
End Property
Private privateLName As String
Public Property LName() As String
Get
Return privateLName
End Get
Set(ByVal value As String)
privateLName = value
End Set
End Property
Private privateDOB As DateTime
Public Property DOB() As DateTime
Get
Return privateDOB
End Get
Set(ByVal value As DateTime)
privateDOB = value
End Set
End Property
Private privateSex As Char
Public Property Sex() As Char
Get
Return privateSex
End Get
Set(ByVal value As Char)
privateSex = value
End Set
End Property
End Class

http://www.dotnetcurry.com/ShowArticle.aspx?ID=260

posted by MyArticles  # 12:41 PM 0 Comments

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