asked on

Finding if Numbers are ranges

I am having the need to determine if numbers read from a database are sequential, in my case its phone numbers

So i will pass the following numbers

5125551122
5125551130
5125551131
5125551132
5125551140

What i want to create as an output is something like that

5125551122
5125551130 - 5125551132
5125551140

it_saige

What determines the grouping? Consider the following:

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Would you expect the output to be -

5125551122 - 5125551132
5125551140

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5125551122 - 5125551129
5125551130 - 5125551132
5125551140

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-saige-

Éric Moreau

we call that Data Islands. Have a look at https://www.simple-talk.com/sql/t-sql-programming/the-sql-of-gaps-and-islands-in-sequences/ and http://sqlmag.com/sql-server-2012/solving-gaps-and-islands-enhanced-window-functions

AlexPonnath

ASKER

The below is what I would want to output

5125551122 - 5125551132
5125551140

AlexPonnath

ASKER

The SQL Data Island is not an options since the Data comes from a text file and there is no SQL Server for this app

it_saige

See if this doesn't do the trick for you:

Module Module1
	Sub Main()
		Dim phoneNumbers = New List(Of String) From {"5125551122", "5125551123", "5125551124", "5125551125", "5125551126", "5125551127", "5125551128", "5125551129", "5125551130", "5125551131", "5125551132", "5125551140"}
		phoneNumbers = phoneNumbers.OrderBy(Function(x) x).ToList()
		Dim results = String.Join(Environment.NewLine, phoneNumbers.GroupAdjacentBy(Function(x, y) (Convert.ToInt64(x) + 1).ToString(String.Format("D{0}", x.Length)) = y).Select(Function(g) New List(Of String)() From {g.First(), g.Last()}.Distinct()).Select(Function(g) String.Join(" - ", g)))
		Console.WriteLine(results)
		Console.ReadLine()
	End Sub
End Module

Module Extensions
	<System.Runtime.CompilerServices.Extension()> _
	Public Iterator Function GroupAdjacentBy(Of T)(source As IEnumerable(Of T), predicate As Func(Of T, T, Boolean)) As IEnumerable(Of IEnumerable(Of T))
		Using e = source.GetEnumerator()
			If e.MoveNext() Then
				Dim list = New List(Of T)() From {e.Current}
				Dim pred = e.Current
				While e.MoveNext()
					If predicate(pred, e.Current) Then
						list.Add(e.Current)
					Else
						Yield list
						list = New List(Of T)() From {e.Current}
					End If
					pred = e.Current
				End While
				Yield list
			End If
		End Using
	End Function
End Module

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Which produces the following output -

-saige-

it_saige

And just tested your original list of numbers:

Module Module1
	Sub Main()
		Dim phoneNumbers = New List(Of String) From {"5125551122", "5125551130", "5125551131", "5125551132", "5125551140"}
		phoneNumbers = phoneNumbers.OrderBy(Function(x) x).ToList()
		Dim results = String.Join(Environment.NewLine, phoneNumbers.GroupAdjacentBy(Function(x, y) (Convert.ToInt64(x) + 1).ToString(String.Format("D{0}", x.Length)) = y).Select(Function(g) New List(Of String)() From {g.First(), g.Last()}.Distinct()).Select(Function(g) String.Join(" - ", g)))
		Console.WriteLine(results)
		Console.ReadLine()
	End Sub
End Module

Module Extensions
	<System.Runtime.CompilerServices.Extension()> _
	Public Iterator Function GroupAdjacentBy(Of T)(source As IEnumerable(Of T), predicate As Func(Of T, T, Boolean)) As IEnumerable(Of IEnumerable(Of T))
		Using e = source.GetEnumerator()
			If e.MoveNext() Then
				Dim list = New List(Of T)() From {e.Current}
				Dim pred = e.Current
				While e.MoveNext()
					If predicate(pred, e.Current) Then
						list.Add(e.Current)
					Else
						Yield list
						list = New List(Of T)() From {e.Current}
					End If
					pred = e.Current
				End While
				Yield list
			End If
		End Using
	End Function
End Module

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Produces the following output -

-saige-

AlexPonnath

ASKER

Yes the console app does work, is there a way you can provide the code for a non console app like a function to which i can just pass one nbr after the other ? My code loops thru a List() which has the nbrs
and i want to be able to get the output as list which i can then loop thru

ASKER CERTIFIED SOLUTION

it_saige

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