使用Zip()合并不同长度的数组而不会丢失值 [英] Merge different length arrays without losing a value using Zip()

问题描述

在下面的代码中，我将合并两个类型为int和string的数组.第一个长度大于第二个长度，因此，最后一个索引(5)不会合并:

In the following code, I'm merging two arrays of types int and string. The first one's length is bigger than the second one, and as a result, the last index (which is 5) doesn't get merged:

int[] numbers = new[] { 1, 2, 3, 4, 5 };
string[] words = new string[] { "one", "two", "three", "four" };

var numbersAndWords = numbers.Zip(words, (n, w) => new { Number = n, Word = w });
foreach (var nw in numbersAndWords)
{
    Console.WriteLine(nw.Number + nw.Word);
}

我想知道一种将其合并的方法.例如，在words中存在的最后一个字符串之后创建一个null或空字符串，并使用它与最后一个numbers索引合并.无法弄清楚.

I would like to know a way of getting it merged. For example, creating a null or empty string after the last one that exists in words and using it to merge with the last numbers index. Couldn't figure it out.

修改: 结果我得到

1one
2two
3three
4four

我想要的结果

1one
2two
3three
4four
5

谢谢！

不是重复项，我的另一个问题是关于在空对象上调用方法.

Not a duplicate, my other question is about calling method on a null object.

推荐答案

您可以轻松编写自己的类似LINQ的扩展方法来实现:

You can easily write your own LINQ-like extension method that will do it:

public static class MyEnumerable
{
    public static IEnumerable<TResult> ZipWithDefault<TFirst, TSecond, TResult>(this IEnumerable<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TSecond, TResult> selector)
    {
        bool firstMoveNext, secondMoveNext;

        using (var enum1 = first.GetEnumerator())
        using (var enum2 = second.GetEnumerator())
        {
            while ((firstMoveNext = enum1.MoveNext()) & (secondMoveNext = enum2.MoveNext()))
                yield return selector(enum1.Current, enum2.Current);

            if (firstMoveNext && !secondMoveNext)
            {
                yield return selector(enum1.Current, default(TSecond));
                while (enum1.MoveNext())
                {
                    yield return selector(enum1.Current, default(TSecond));
                }
            }
            else if (!firstMoveNext && secondMoveNext)
            {
                yield return selector(default(TFirst), enum2.Current);
                while (enum2.MoveNext())
                {
                    yield return selector(default(TFirst), enum2.Current);
                }
            }
        }
    }
}

但是，如果您的源始终是一对数组，则简单地使用for循环可能会更容易:

But if your source is always a pair of arrays, it might be easier to simply use for loop:

public static IEnumerable<TResult> ZipWithDefault<TFirst, TSecond, TResult>(this TFirst[] first, TSecond[] second, Func<TFirst, TSecond, TResult> selector)
{
    var maxLength = Math.Max(first.Length, second.Length);

    for(var i = 0; i < maxLength; i++)
    {
        var firstItem = i < first.Length ? first[i] : default(TFirst);
        var secondItem = i < second.Length ? second[i] : default(TSecond);
        yield return selector(firstItem, secondItem);

    }
}

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