Como: Combinar e comparar as coleções de seqüência de caracteres (LINQ)
Este exemplo mostra como mesclar arquivos que contêm as linhas de texto e, em seguida, classificar os resultados. Especificamente, mostra como executar uma concatenação simple, uma união e uma interseção em dois conjuntos de linhas de texto.
Para configurar o projeto e os arquivos de texto
Copie esses nomes em um arquivo de texto chamado names1.txt e salve-o na sua pasta de solução:
Bankov, Peter Holm, Michael Garcia, Hugo Potra, Cristina Noriega, Fabricio Aw, Kam Foo Beebe, Ann Toyoshima, Tim Guy, Wey Yuan Garcia, DebraCopie esses nomes em um arquivo de texto chamado names2.txt e salve-o na sua pasta de solução. Observe que os dois arquivos têm alguns nomes em comum.
Liu, Jinghao Bankov, Peter Holm, Michael Garcia, Hugo Beebe, Ann Gilchrist, Beth Myrcha, Jacek Giakoumakis, Leo McLin, Nkenge El Yassir, Mehdi
Exemplo
Class ConcatenateStrings
Shared Sub Main()
' Create the IEnumerable data sources.
Dim fileA As String() = System.IO.File.ReadAllLines("../../../names1.txt")
Dim fileB As String() = System.IO.File.ReadAllLines("../../../names2.txt")
' Simple concatenation and sort.
Dim concatQuery = fileA.Concat(fileB).OrderBy(Function(name) name)
' Pass the query variable to another function for execution
OutputQueryResults(concatQuery, "Simple concatenation and sort. Duplicates are preserved:")
' New query. Concatenate files and remove duplicates
Dim uniqueNamesQuery = fileA.Union(fileB).OrderBy(Function(name) name)
OutputQueryResults(uniqueNamesQuery, "Union removes duplicate names:")
' New query. Find the names that occur in both files.
Dim commonNamesQuery = fileA.Intersect(fileB)
OutputQueryResults(commonNamesQuery, "Merge based on intersect: ")
' New query in three steps for better readability
' First filter each list separately
Dim nameToSearch As String = "Garcia"
Dim mergeQueryA As IEnumerable(Of String) = From name In fileA
Let n = name.Split(New Char() {","})
Where n(0) = nameToSearch
Select name
Dim mergeQueryB = From name In fileB
Let n = name.Split(New Char() {","})
Where n(0) = nameToSearch
Select name
' Create a new query to concatenate and sort results. Duplicates are removed in Union.
' Note that none of the queries actually executed until the call to OutputQueryResults.
Dim mergeSortQuery = mergeQueryA.Union(mergeQueryB).OrderBy(Function(str) str)
' Now execute mergeSortQuery
OutputQueryResults(mergeSortQuery, "Concat based on partial name match """ & nameToSearch & """ from each list:")
' Keep console window open in debug mode.
Console.WriteLine("Press any key to exit.")
Console.ReadKey()
End Sub
Shared Sub OutputQueryResults(ByVal query As IEnumerable(Of String), ByVal message As String)
Console.WriteLine(System.Environment.NewLine & message)
For Each item As String In query
Console.WriteLine(item)
Next
Console.WriteLine(query.Count & " total names in list")
End Sub
End Class
' Output:
' Simple concatenation and sort. Duplicates are preserved:
' Aw, Kam Foo
' Bankov, Peter
' Bankov, Peter
' Beebe, Ann
' Beebe, Ann
' El Yassir, Mehdi
' Garcia, Debra
' Garcia, Hugo
' Garcia, Hugo
' Giakoumakis, Leo
' Gilchrist, Beth
' Guy, Wey Yuan
' Holm, Michael
' Holm, Michael
' Liu, Jinghao
' McLin, Nkenge
' Myrcha, Jacek
' Noriega, Fabricio
' Potra, Cristina
' Toyoshima, Tim
' 20 total names in list
' Union removes duplicate names:
' Aw, Kam Foo
' Bankov, Peter
' Beebe, Ann
' El Yassir, Mehdi
' Garcia, Debra
' Garcia, Hugo
' Giakoumakis, Leo
' Gilchrist, Beth
' Guy, Wey Yuan
' Holm, Michael
' Liu, Jinghao
' McLin, Nkenge
' Myrcha, Jacek
' Noriega, Fabricio
' Potra, Cristina
' Toyoshima, Tim
' 16 total names in list
' Merge based on intersect:
' Bankov, Peter
' Holm, Michael
' Garcia, Hugo
' Beebe, Ann
' 4 total names in list
' Concat based on partial name match "Garcia" from each list:
' Garcia, Debra
' Garcia, Hugo
' 2 total names in list
class MergeStrings
{
static void Main(string[] args)
{
//Put text files in your solution folder
string[] fileA = System.IO.File.ReadAllLines(@"../../../names1.txt");
string[] fileB = System.IO.File.ReadAllLines(@"../../../names2.txt");
//Simple concatenation and sort. Duplicates are preserved.
IEnumerable<string> concatQuery =
fileA.Concat(fileB).OrderBy(s => s);
// Pass the query variable to another function for execution.
OutputQueryResults(concatQuery, "Simple concatenate and sort. Duplicates are preserved:");
// Concatenate and remove duplicate names based on
// default string comparer.
IEnumerable<string> uniqueNamesQuery =
fileA.Union(fileB).OrderBy(s => s);
OutputQueryResults(uniqueNamesQuery, "Union removes duplicate names:");
// Find the names that occur in both files (based on
// default string comparer).
IEnumerable<string> commonNamesQuery =
fileA.Intersect(fileB);
OutputQueryResults(commonNamesQuery, "Merge based on intersect:");
// Find the matching fields in each list. Merge the two
// results by using Concat, and then
// sort using the default string comparer.
string nameMatch = "Garcia";
IEnumerable<String> tempQuery1 =
from name in fileA
let n = name.Split(',')
where n[0] == nameMatch
select name;
IEnumerable<string> tempQuery2 =
from name2 in fileB
let n2 = name2.Split(',')
where n2[0] == nameMatch
select name2;
IEnumerable<string> nameMatchQuery =
tempQuery1.Concat(tempQuery2).OrderBy(s => s);
OutputQueryResults(nameMatchQuery, String.Format("Concat based on partial name match \"{0}\":", nameMatch));
// Keep the console window open in debug mode.
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
static void OutputQueryResults(IEnumerable<string> query, string message)
{
Console.WriteLine(System.Environment.NewLine + message);
foreach (string item in query)
{
Console.WriteLine(item);
}
Console.WriteLine("{0} total names in list", query.Count());
}
}
/* Output:
Simple concatenate and sort. Duplicates are preserved:
Aw, Kam Foo
Bankov, Peter
Bankov, Peter
Beebe, Ann
Beebe, Ann
El Yassir, Mehdi
Garcia, Debra
Garcia, Hugo
Garcia, Hugo
Giakoumakis, Leo
Gilchrist, Beth
Guy, Wey Yuan
Holm, Michael
Holm, Michael
Liu, Jinghao
McLin, Nkenge
Myrcha, Jacek
Noriega, Fabricio
Potra, Cristina
Toyoshima, Tim
20 total names in list
Union removes duplicate names:
Aw, Kam Foo
Bankov, Peter
Beebe, Ann
El Yassir, Mehdi
Garcia, Debra
Garcia, Hugo
Giakoumakis, Leo
Gilchrist, Beth
Guy, Wey Yuan
Holm, Michael
Liu, Jinghao
McLin, Nkenge
Myrcha, Jacek
Noriega, Fabricio
Potra, Cristina
Toyoshima, Tim
16 total names in list
Merge based on intersect:
Bankov, Peter
Holm, Michael
Garcia, Hugo
Beebe, Ann
4 total names in list
Concat based on partial name match "Garcia":
Garcia, Debra
Garcia, Hugo
Garcia, Hugo
3 total names in list
*/
Compilando o código
Criar um Visual Studio o projeto que se destina a .NET Framework versão 3.5. Por padrão, o projeto tem uma referência a System.Core.dll e um using diretiva (C#) ou Imports instrução (Visual Basic) para o namespace System. LINQ. No C# projetos, adicione um using a diretiva para o namespace System. IO.
Copie este código em seu projeto.
Pressione F5 para compilar e executar o programa.
Pressione qualquer tecla para sair da janela do console.