排序基于排序值的数组散列数组(Sorting an Array of hashes based on

我有散列的阵列如下面给出：

user_quizzes = [{:id => 3897, :quiz_id => 1793, :user_id => 252}, {:id => 3897, :quiz_id => 1793, :user_id => 475}, {:id => 3897, :quiz_id => 1793, :user_id => 880}, {:id => 3897, :quiz_id => 1793, :user_id => 881}, {:id => 3897, :quiz_id => 1793, :user_id => 882}, {:id => 3897, :quiz_id => 1793, :user_id => 883}, {:id => 3897, :quiz_id => 1793, :user_id => 884}]

另外，基于特定的条件我把“的值user_id ”键从相同的散列和排序它和下同阵列被下式给出：

sorted_user_ids = [880, 881, 882, 883, 884, 475, 252]

现在，我需要的user_quizzes基于顺序上重新整理user_id在sorted_user_ids阵列。

任何人都可以请帮我在这。 :)

Answer 1:

使用Enumerable#sort_by或Array#sort_by! ，您可以指定将用于比较的关键：

user_quizzes = [
  {:id => 3897, :quiz_id => 1793, :user_id => 252},
  {:id => 3897, :quiz_id => 1793, :user_id => 475},
  {:id => 3897, :quiz_id => 1793, :user_id => 880},
  {:id => 3897, :quiz_id => 1793, :user_id => 881},
  {:id => 3897, :quiz_id => 1793, :user_id => 882},
  {:id => 3897, :quiz_id => 1793, :user_id => 883},
  {:id => 3897, :quiz_id => 1793, :user_id => 884}
]
sorted_user_ids = [880, 881, 882, 883, 884, 475, 252]
user_quizzes.sort_by { |x| sorted_user_ids.index(x[:user_id]) }
# => [{:id=>3897, :quiz_id=>1793, :user_id=>880},
#     {:id=>3897, :quiz_id=>1793, :user_id=>881},
#     {:id=>3897, :quiz_id=>1793, :user_id=>882},
#     {:id=>3897, :quiz_id=>1793, :user_id=>883},
#     {:id=>3897, :quiz_id=>1793, :user_id=>884},
#     {:id=>3897, :quiz_id=>1793, :user_id=>475},
#     {:id=>3897, :quiz_id=>1793, :user_id=>252}]

附注： sorted_user_ids.index(x[:user_id])可能成为瓶颈（重复O（n）的操作），如果数组是巨大的。

建立映射的哈希user_id s到在这种情况下命令：

sorted_user_ids = [880, 881, 882, 883, 884, 475, 252]
order = Hash[sorted_user_ids.each_with_index.to_a]
# => {880=>0, 881=>1, 882=>2, 883=>3, 884=>4, 475=>5, 252=>6}
user_quizzes.sort_by { |x| order[x[:user_id]] }
# => same as above.

文章来源: Sorting an Array of hashes based on an Array of sorted values