在Ruby中将数组拆分为多个小数组的最佳方法

Question

根据某些条件将数组拆分成多个数组的最简单方法是什么？在我的场景中,我需要将整数和字符串值移动到不同的数组.我尝试过split方法,但没有按预期工作.

x=[1,2,3,"a","b",4]
x.split {|item| item.kind_of? Fixnum}

在C#中,有一个group by选项Linq,可以帮助您根据条件对对象进行分组.是否有类似的方法Object(不使用activerecord)？

有一个简单的方法吗？

Answer 1

您正在寻找Enumerable#partition:

x = [1, 2, 3, "a", "b", 4]
numbers, not_numbers = x.partition{|item| item.kind_of?(Fixnum)}
# => [[1, 2, 3, 4], ["a", "b"]]

Answer 2

只是为了向池中添加更多解决方案:

x = [1,2,3,"a","b",4]

numbers = x.select{ |e| e.is_a?(Fixnum) } # => [1, 2, 3, 4]
letters = x - numbers # => ["a", "b"]

numbers = x.select{ |e| e.kind_of?(Fixnum) } # => [1, 2, 3, 4]
letters = x - numbers # => ["a", "b"]

要么

(numbers, letters) = x.group_by {|a| a.class}.values_at(Fixnum, String)
numbers # => [1, 2, 3, 4]
letters # => ["a", "b"]

除了一些显示微妙变化影响速度的基准:

require 'benchmark'

x = [1,2,3,"a","b",4] * 100
n = 10_000
Benchmark.bm do |bench|
  bench.report { n.times {
    numbers = x.select{ |e| e.is_a?(Fixnum) }
    letters = x - numbers
  }}

  bench.report { n.times {
    numbers = x.select{ |e| e.kind_of?(Fixnum) }
    letters = x - numbers
  }}

  bench.report { n.times {
    (numbers, letters) = x.group_by {|a| a.class}.values_at(Fixnum, String)
  }}

  bench.report { n.times {
    numbers, not_numbers = x.partition{|item| item.kind_of? Fixnum}
  }}
end
# >>       user     system      total        real
# >>   4.270000   0.010000   4.280000 (  4.282922)
# >>   4.290000   0.000000   4.290000 (  4.288720)
# >>   5.160000   0.010000   5.170000 (  5.163695)
# >>   3.720000   0.000000   3.720000 (  3.721459)

Answer 3

尝试:

x.group_by {|x| x.class}

您可以通过调用to_a结果来获取一个数组,在您给出的示例中将返回该结果:

[[Fixnum, [1, 2, 3, 4]], [String, ["a", "b"]]]