如何更好地處理散列數組

Question

下面是來自PGResult集合的散列數組。

result = [ 
    {"type" => 1 , "original" => "true", "count" => "10"}, 
    {"type" => 1 , "original" => "false", "count" => "20"}, 
    {"type" => 2 , "original" => "false", "count" => "30"}, 
    {"type" => 2 , "original" => "true", "count" => "40"}, 
    {"type" => 3 , "original" => "true", "count" => "50"}, 
    {"type" => 3 , "original" => "false", "count" => "60"} 
] 

我想處理上面的哈希數組爲下面的格式。 total_count =原始計數（「真」） - 每種類型的原始計數（「假」）！

[ 
    {"type" => 1, "total_count" => "-10"}, 
    {"type" => 2, "total_count" => "10"}, 
    {"type" => 3, "total_count" => "-10"} 
] 

任何提示處理上述數組？

Answer 1

result.group_by {|h| h['type']}.values.map do |h1, h2| 
    new_hash = {"type" => h1["type"]} 
    new_hash["total_count"] = h1["original"] == "false" ? h1["count"].to_i - h2["count"].to_i : h2["count"].to_i - h1["count"].to_i 
    new_hash 
end 
# => [{"type"=>1, "total_count"=>10}, {"type"=>2, "total_count"=>-10}, {"type"=>3, "total_count"=>10}] 

Answer 2

如何像：

result = [ 
    {"type" => 1 , "original" => "true", "count" => "10"}, 
    {"type" => 1 , "original" => "false", "count" => "20"}, 
    {"type" => 2 , "original" => "false", "count" => "30"}, 
    {"type" => 2 , "original" => "true", "count" => "40"}, 
    {"type" => 3 , "original" => "true", "count" => "50"}, 
    {"type" => 3 , "original" => "false", "count" => "60"} 
] 

# will be used to extract "proper" value - positive or negative 
to_value = -> (group) do 
    value = group["count"].to_i 
    group["original"] == "false" ? -value : value 
end 

groups = result.group_by { |h| h["type"] } 

counts = groups.map do |num, group| 
    { "type" => num, 
    "total_count" => group.map(&to_value).inject(:+) } 
end 

p counts 
# => [{"type"=>1, "total_count"=>-10}, {"type"=>2, "total_count"=>10}, {"type"=>3, "total_count"=>-10}] 

希望幫助！

感謝您對lambda的建議！@engineersmnky！