如何在 Ruby 中返回数组的一部分? [英] How to return a part of an array in Ruby?

问题描述

使用 Python 中的列表，我可以使用以下代码返回其中的一部分:

With a list in Python I can return a part of it using the following code:

foo = [1,2,3,4,5,6]
bar = [10,20,30,40,50,60]
half = len(foo) / 2
foobar = foo[:half] + bar[half:]

由于 Ruby 在数组中做所有事情，我想知道是否有类似的东西.

Since Ruby does everything in arrays I wonder if there is something similar to that.

推荐答案

是的，Ruby 的数组切片语法与 Python 非常相似.这是数组索引方法的 ri 文档:

Yes, Ruby has very similar array-slicing syntax to Python. Here is the ri documentation for the array index method:

--------------------------------------------------------------- Array#[]
     array[index]                -> obj      or nil
     array[start, length]        -> an_array or nil
     array[range]                -> an_array or nil
     array.slice(index)          -> obj      or nil
     array.slice(start, length)  -> an_array or nil
     array.slice(range)          -> an_array or nil
------------------------------------------------------------------------
     Element Reference---Returns the element at index, or returns a 
     subarray starting at start and continuing for length elements, or 
     returns a subarray specified by range. Negative indices count 
     backward from the end of the array (-1 is the last element). 
     Returns nil if the index (or starting index) are out of range.

        a = [ "a", "b", "c", "d", "e" ]
        a[2] +  a[0] + a[1]    #=> "cab"
        a[6]                   #=> nil
        a[1, 2]                #=> [ "b", "c" ]
        a[1..3]                #=> [ "b", "c", "d" ]
        a[4..7]                #=> [ "e" ]
        a[6..10]               #=> nil
        a[-3, 3]               #=> [ "c", "d", "e" ]
        # special cases
        a[5]                   #=> nil
        a[6, 1]                #=> nil
        a[5, 1]                #=> []
        a[5..10]               #=> []

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