ruby - 如何合并多个哈希？

Question

现在，我正在合并两个这样的哈希：

department_hash  = self.parse_department html
super_saver_hash = self.parse_super_saver html

final_hash = department_hash.merge(super_saver_hash)

输出：

{:department=>{"宠物用品"=>{"鸟"=>16281, "猫"=>245512, "狗"=>513926, "鱼和水生宠物"=>46811, "马"=>14805 , "昆虫"=>364, "爬行动物和两栖动物"=>5816, "小动物"=>19769}}, :super_saver=>{"Free Super Saver Shipping"=>126649}}

但现在我想在未来合并更多。例如：

department_hash  = self.parse_department html
super_saver_hash = self.parse_super_saver html
categories_hash  = self.parse_categories html

如何合并多个哈希？

Answer 1

怎么样：

[department_hash, super_saver_hash, categories_hash].reduce &:merge

Answer 2

您可以merge再次调用：

h1 = {foo: :bar}
h2 = {baz: :qux}
h3 = {quux: :garply}

h1.merge(h2).merge(h3)
#=> {:foo=>:bar, :baz=>:qux, :quux=>:garply}

Answer 3

您可以使用以下方式执行以下操作Enumerable#inject：

h = {}
arr = [{:a=>"b"},{"c" => 2},{:a=>4,"c"=>"Hi"}]
arr.inject(h,:update)
# => {:a=>4, "c"=>"Hi"}
arr.inject(:update)
# => {:a=>4, "c"=>"Hi"}

Answer 4

在经历了这个问题及其答案之后，我花了一段时间才弄清楚如何合并多嵌套哈希。事实证明，我错误地遍历了哈希集合，导致了各种null值问题。

此示例命令行应用程序显示如何使用 和 的组合合并多个哈希store，merge!具体取决于它们是否是顶级哈希键。它使用带有一些已知键名的命令行参数进行分类。

下面提供了 Gist URL 的完整代码：

# Ruby - A nested hash example
# Load each pair of args on the command-line as a key-value pair
# For example from CMD.exe:
# call ruby.exe ruby_nested_hash_example.rb Age 30 Name Mary Fav_Hobby Ataraxia Fav_Number 42
# Output would be:
    # {
      # "data_info": {
        # "types": {
          # "nums": {
            # "Age": 30,
            # "Fav_Number": 42
          # },
          # "strings": {
            # "Name": "Mary",
            # "Fav_Hobby": "Ataraxia"
          # }
        # },
        # "data_id": "13435436457"
      # }
    # }


if (ARGV.count % 2 != 0) || (ARGV.count < 2)
    STDERR.puts "You must provide an even amount of command-line args to make key-value pairs.\n"
    abort
end
require 'json'


cmd_hashes = {}
nums = {}
strings = {}
types = {}
#FYI `tl` == top-level
all_tl_keys = {}
data_info = {}
data_id = {:data_id => "13435436457"}


_key = ""
_value = ""
element = 0
ARGV.each do |i|
    if element % 2 == 0
        _key=i
    else
        if (i.to_i!=0) && (i!=0)
            _value=i.to_i
        else
            _value=i
        end
    end
    if (_key != "") && (_value != "")
        cmd_hashes.store(_key, _value)
        _key = ""
        _value = ""
    end
    element+=1
end


cmd_hashes.each do |key, value|
    if value.is_a? Numeric
        nums.store(key, value)
    else
        strings.store(key, value)
    end
end


if nums.size        > 0;    types.merge!(:nums => nums)                 end
if strings.size     > 0;    types.merge!(:strings => strings)           end
if types.size       > 0;    all_tl_keys.merge!(:types => types)         end
if data_id.size     > 0;    all_tl_keys.merge!(data_id)                 end
if all_tl_keys.size > 0;    data_info.merge!(:data_info => all_tl_keys) end


if data_info.size   > 0;    puts JSON.pretty_generate(data_info)        end

Answer 5

假设你正在arr = [{x: 10},{y: 20},{z: 30}] 做

arr.reduce(:merge)