Ruby将密钥合并到csv字符串中 [英] Ruby merge hashes putting keys into csv string

问题描述

在Ruby中有一种聪明的方法来实现以下功能：

  hash1 = {a=> 1，b=> 2，d=> 3} 
 hash2 = {a=> 4，b=> 5，c=> 7} 
 hash3 = {a=> 4，d=> 7，e=> 9} 
 puts带输出的hash1.csvMerge（hash2）.csvMerge（hash3）
  

存在：

  {a=> 1,4,4，
b=> 2,5,0，
c=> 0,7,0，
d=> 3,0,7，
e=> 0,0,9} 
  

我想要做的是合并一堆Ruby散列，在实践中，我有超过一打，成为一个单一的散列，其中的值组合成一个逗号分隔的字符串。

<$ p $ {code> hashes = [hash1，hash2，hash3]
keys = hashes.inject（{}）{| hh，h | hh = hh.merge（h）; hh} .keys＃所有密钥的集合＃
default_hash = keys.inject（{}）{| d，k | d [k] = 0; d}＃所有密钥的值为0的散列＃
complemented_hashes = hashes.map {| h | default_hash.merge（h）}＃缺少值填入＃

p哈希值[complemented_hashes.map {| h | h.to_a} .flatten（1）.group_by {| k，v | ķ}。
map {| k，v | [k，v.map {| k，v | v} .join（，）]}]

Is there a clever way to achieve the following in Ruby?

hash1 = { "a" => 1, "b" => 2, "d" => 3}
hash2 = { "a" => 4, "b" => 5, "c" => 7}
hash3 = { "a" => 4, "d" => 7, "e" => 9}
puts hash1.csvMerge(hash2).csvMerge(hash3)

with the output being:

{ "a" => "1,4,4",
  "b" => "2,5,0",
  "c" => "0,7,0",
  "d" => "3,0,7",
  "e" => "0,0,9" }

What I'm trying to do is merge a bunch of Ruby hashes, in practice I have over a dozen, into a single hash where the values are combined into a comma separated string.

解决方案

hashes = [hash1, hash2, hash3]
keys = hashes.inject({}){|hh, h| hh = hh.merge(h); hh}.keys   # the set of all keys #
default_hash = keys.inject({}){|d, k| d[k] = 0; d}    # hash with value 0 for all keys #
complemented_hashes = hashes.map{|h| default_hash.merge(h)} # missing values filled in #

p Hash[complemented_hashes.map{|h| h.to_a}.flatten(1).group_by{|k, v| k}.
map{|k, v| [k, v.map{|k, v| v}.join(",")]}]

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