Arrays 从数组中选取键值对

我有一个像这样的数组

[
  "---\n",
  ":date: 2018-07-31\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-01\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-22\n  :estimated_hours: 4.0\n  :remaining_hours: 0.0\n "
]

我想选择key:date的所有值。我读到我可以使用Enumerableselect，但我不知道怎么做。有人能帮上忙吗？

希望这能帮上忙

data = ["---\n", ":date: 2018-07-31\n :estimated_hours: 4.0\n :remaining_hours: 4.0\n ", ":date: 2018-08-01\n :estimated_hours: 4.0\n :remaining_hours: 4.0\n ", ":date: 2018-08-22\n :estimated_hours: 4.0\n :remaining_hours: 0.0\n "]

DATE_REGEX = /:date:\s(.*)\n/

dates = data.map do |record|
  record.match(DATE_REGEX)[1] if record.match(REGEX)
end.compact

可以与正则表达式参数一起使用，并且：

或

---

？由于这看起来非常像YAML，尽管它需要一点消毒，我会选择：

a = [
  "---\n",
  ":date: 2018-07-31\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-01\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-22\n  :estimated_hours: 4.0\n  :remaining_hours: 0.0\n "
].map(&:rstrip)

require 'yaml'

data = a[1..-1].map {|s| YAML.load(s.gsub("  ", ""))}
#=> [
#  {:date=>#<Date: 2018-07-31 ((2458331j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>4.0}, 
#  {:date=>#<Date: 2018-08-01 ((2458332j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>4.0}, 
#  {:date=>#<Date: 2018-08-22 ((2458353j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>0.0}]

data.map {|h| h[:date] } 
#=> [#<Date: 2018-07-31 ((2458331j,0s,0n),+0s,2299161j)>, 
#     #<Date: 2018-08-01 ((2458332j,0s,0n),+0s,2299161j)>, 
#     #<Date: 2018-08-22 ((2458353j,0s,0n),+0s,2299161j)>]

---

您将始终有一个soln，但我可以问一下谁正在生成此数组。也许你可以调整它，像使用散列或其他更有意义的东西一样使用它。你从哪里得到这个数组的？看起来，当您应该只使用YAML时，您将YAML文件拆分为新行。解析该文件，然后您将获得适当的哈希和数组。如果您的数组是这样的，让我们尝试下面给定的解决方案。数组是数据库的结果。我在数据库中有一个文本列，它将所有这些信息存储在一个列中。我已经把它带到了应用层，现在我需要按日期列分组，并继续进一步的功能。我将尝试下面的解决方案，并让您知道。感谢您的帮助也许，OP希望对结果应用展平，但这并不重要。更改为arr.join.scan/：date:\d{4}-\d{2}-\d{2}/.flatte以匹配OP的预期结果您不需要/：date:\s.\n/？要使捕获组的匹配不贪婪，那么匹配将在字符串中的第一行而不是最后一行结束？

arr = ["---\n",
       ":date: 2018-07-31\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
       ":date: 2018-08-01\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
       ":date: 2018-08-22\n  :estimated_hours: 4.0\n  :remaining_hours: 0.0\n "]

arr.join.scan(/:date: (\d{4}-\d{2}-\d{2})/).flatten
  #=> ["2018-07-31", "2018-08-01", "2018-08-22"]

arr.join.scan(/(?<=:date: )\d{4}-\d{2}-\d{2}/).flatten
  #=> ["2018-07-31", "2018-08-01", "2018-08-22"]

arr.join.gsub(/(?<=:date: )\d{4}-\d{2}-\d{2}/).to_a
  #=> ["2018-07-31", "2018-08-01", "2018-08-22"]

a = [
  "---\n",
  ":date: 2018-07-31\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-01\n  :estimated_hours: 4.0\n  :remaining_hours: 4.0\n ",
  ":date: 2018-08-22\n  :estimated_hours: 4.0\n  :remaining_hours: 0.0\n "
].map(&:rstrip)

require 'yaml'

data = a[1..-1].map {|s| YAML.load(s.gsub("  ", ""))}
#=> [
#  {:date=>#<Date: 2018-07-31 ((2458331j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>4.0}, 
#  {:date=>#<Date: 2018-08-01 ((2458332j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>4.0}, 
#  {:date=>#<Date: 2018-08-22 ((2458353j,0s,0n),+0s,2299161j)>, :estimated_hours=>4.0, :remaining_hours=>0.0}]

data.map {|h| h[:date] } 
#=> [#<Date: 2018-07-31 ((2458331j,0s,0n),+0s,2299161j)>, 
#     #<Date: 2018-08-01 ((2458332j,0s,0n),+0s,2299161j)>, 
#     #<Date: 2018-08-22 ((2458353j,0s,0n),+0s,2299161j)>]