如何将数组分成一组n个元素？

Question

在c#4中将数组分组为n个元素数组的列表的最佳方法是什么？

例如

string[] testArray = { "s1", "s2", "s3", "s4", "s5", "s6", "s7", "s8" };

如果我们采用n = 3,应该拆分成.

string[] A1 = {"s1", "s2", "s3"};
string[] A2 = {"s4", "s5", "s6"};
string[] A3 = {"s7", "s8"};

使用LINQ可能是一种简单的方法吗？

Answer 1

这将生成一个包含3个元素的字符串数组:

int i = 0;
var query = from s in testArray
            let num = i++
            group s by num / 3 into g
            select g.ToArray();
var results = query.ToArray();

Answer 2

我不认为有一个很好的内置方法,但你可以编写如下的方法.

public static IEnumerable<IEnumerable<T>> GroupInto<T>(
  this IEnumerable<T> source,
  int count) {

  using ( var e = source.GetEnumerator() ) {
    while ( e.MoveNext() ) { 
      yield return GroupIntoHelper(e, count);
    }
  }    
}

private static IEnumerable<T> GroupIntoHelper<T>(
  IEnumerator<T> e,
  int count) {

  do {
    yield return e.Current;
    count--;
  } while ( count > 0 && e.MoveNext());
}

Answer 3

int size = 3;
var results = testArray.Select((x, i) => new { Key = i / size, Value = x })
                       .GroupBy(x => x.Key, x => x.Value, (k, g) => g.ToArray())
                       .ToArray();

如果您不介意输入结果IEnumerable<IEnumerable<T>>而不是T[][]那么您可以ToArray完全省略调用:

int size = 3;
var results = testArray.Select((x, i) => new { Key = i / size, Value = x })
                       .GroupBy(x => x.Key, x => x.Value);