[英]Merging multiple arrays and get an array of common elements as output
[英]Get elements in common from array of arrays
假设我有一个像这样的数组:
[
[1, 2, 3, 4],
[3, 4, 5, 6],
[4, 5, 6, 8]
]
我需要使它们之间的元素相同。 我该如何实现?
结果应该是
common_elements([[1, 2, 3, 4], [3, 4, 5, 6], [4, 5, 6, 8]]) # => [4]
[[1, 2, 3, 4], [3, 4, 5, 6], [4, 5, 6, 8]].reduce(:&) # => [4]
Array#&方法为您设置交集:
[1, 2, 3] & [2, 3, 4] # => [2, 3]
Enumerable#reduce方法可以使用以下操作组合给定数组中的值:
[1, 2, 3].reduce(:+) # => 6
这是“手动大声笑”的另一种实现方法...分别迭代嵌套数组[[0],[1],[2]],
然后迭代每个嵌套数组并使用include ary [ pos] .include?(x),在所有三个嵌套数组之间使用AND来查找相交的值,这会很慢,但是如果您想添加更多条件则很方便。
user> ary = [ [1,2,3,4], [3,4,5,6], [4,5,6,8] ]
=> [[1, 2, 3, 4], [3, 4, 5, 6], [4, 5, 6, 8]]
user> ary.each { |f| f.each {|x|
puts "#{x}" if ary[0].include?(x) && ary[1].include?(x) &&
ary[2].include?(x) }}
4
4
4
或者简单地说,
2.1.2 :003 > ary = [ [1,2,3,4], [3,4,5,6], [4,5,6,8] ].inject(:&)
=> [4]
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