Ruby 按键值分组哈希

Question

我有一个数组，它是由 MongoDB 执行的 map/reduce 方法输出的，它看起来像这样:

[{"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>299.0}, 
{"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>244.0}, 
{"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>1.0, "count"=>204.0}, 
{"minute"=>45.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>510.0}, 
{"minute"=>45.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>437.0}, 
{"minute"=>0.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>469.0}, 
{"minute"=>0.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>477.0}, 
{"minute"=>15.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>481.0}, 
{"minute"=>15.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>401.0}, 
{"minute"=>30.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>468.0}, 
{"minute"=>30.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>448.0}, 
{"minute"=>45.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>0.0, "count"=>485.0}, 
{"minute"=>45.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "type"=>10.0, "count"=>518.0}] 

您会注意到 type 有三个不同的值，在本例中为 0、1 和 2，现在要做的是按其 type 键的值对这个哈希数组进行分组，例如，这个数组最终看起来像:

{
  :type_0 => [
    {"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>299.0}, 
    {"minute"=>45.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>510.0}, 
    {"minute"=>0.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>469.0}, 
    {"minute"=>15.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>481.0}, 
    {"minute"=>30.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>468.0}, 
    {"minute"=>45.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>485.0}
  ],

  :type_1 => [
    {"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>204.0}
  ],

  :type_10 => [
    {"minute"=>30.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>244.0}, 
    {"minute"=>45.0, "hour"=>15.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>437.0},
    {"minute"=>0.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>477.0}, 
    {"minute"=>15.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>401.0}, 
    {"minute"=>30.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>448.0}, 
    {"minute"=>45.0, "hour"=>16.0, "date"=>5.0, "month"=>9.0, "year"=>2011.0, "count"=>518.0}
  ]
} 

所以我知道这些示例数组确实很大，但我认为这可能是一个比我想象的更简单的问题

所以基本上每个哈希数组都将按其 type 键的值分组，然后作为带有每种类型数组的哈希返回，任何帮助都会非常有帮助，即使只是一些有用的提示也将不胜感激。

Answer 1

array.group_by {|x| x['type']}

或者如果你想要符号键，你甚至可以

array.group_by {|x| "type_#{x['type']}".to_sym}

我认为这最能表达“所以基本上每个哈希数组都会按其类型键的值分组，然后作为哈希返回每个类型的数组”，即使它在输出哈希中单独留下 :type 键。