Question

我有一个字符串数组，我从文件x
我有一个空数组y
某些字符串对象是整数
如何通过使用to_a?

现在我正在尝试

x.each do |s| if s.to_i.is_a?(Integer) y << s end end

但这只是将所有内容转换为整数并将其填入y，有没有办法查看对象是否真的来自Integer类？

编辑添加样本输入/输出

x = [ "This", "is", "a", "random", "amalgamation", "of", "text", "and", "a", "bunch", "of", "numbers", "111113087403957304739703975", "how", "can", "I", "read", "this", "in." ] y = [ 111113087403957304739703975 ]

Answer 1

x = [ "This", "is", "a", "random", "amalgamation", "of", "text", "and", "a",
      "bunch", "of", "numbers", "111113087403957304739703975", "how", "can", "I",
      "read", "this", "in." ]

y = [ 111113087403957304739703975 ]

def extract_integers(array)
  array.select { |v| v.match(/\A\d+\z/) }.map(&:to_i)
  # or (simpler, as suggested by @theTinMan)
  array.reject { |v| v[/\D/] }.map(&:to_i)
end

p extract_integers(x)      #=> [111113087403957304739703975]
p extract_integers(x) == y #=> true

Answer 2

s.match(/^\d+$/)将匹配仅包含数字的字符串，因此您可以使用此字符串来测试字符串

Answer 3

您可以使用Enumerable#grep：

arr = %w[9 cats on 33 hot tin roofs] 
   #=> ["9", "cats", "on", "33", "hot", "tin", "roofs"]

arr.grep /^\d+$/
  #=> ["9", "33"]
arr.grep(/^\d+$/).map(&:to_i)
  #=> [9, 33]

Answer 4

x.each do |s|
    begin
      Integer(s)
    rescue ArgumentError
    else
      y << s
    end
end

如果应用于不解析为整数的字符串，Integer()会引发ArgumentError。您可以使用它来查找整数字符串。

Answer 5

运行基准测试总是很有趣，也很有用：

require 'fruity'

x = [ "This", "is", "a", "random", "amalgamation", "of", "text", "and", "a",
  "bunch", "of", "numbers", "111113087403957304739703975", "how", "can", "I",
  "read", "this", "in." ]

def extract_integers(array)
  array.select { |v| v.match(/\A\d+\z/) }.map(&:to_i)
end

def extract_integers_reject(array)
  array.reject { |v| v[/\D/] }.map(&:to_i)
end


compare do
  use_exception {
    y = []
    x.each do |s|
      begin
        Integer(s)
      rescue ArgumentError
      else
        y << s.to_i
      end
    end
    y
  }

  use_extract_integers {
    extract_integers(x)
  }

  use_extract_integers_reject {
    extract_integers_reject(x)
  }
end

在我的机器上运行会产生以下结果：

Running each test 256 times. Test will take about 1 second.
use_extract_integers_reject is faster than use_extract_integers by 30.000000000000004% ± 10.0%
use_extract_integers is faster than use_exception by 6x ± 0.1

注意，y << s已更改为y << s.to_i，以使输出全部匹配。

我可能会使用像这样的ArgumentError救援来简化代码：

x.each do |s|
  begin
    y << Integer(s)
  rescue ArgumentError
  end
end

Ruby通过检查对象是否继承某个类来分隔字符串数组

5 个答案: