如何比较两个散列?

I am trying to compare two Ruby Hashes using the following code:

我正在尝试使用以下代码来比较两个Ruby散列:

#!/usr/bin/env ruby

require "yaml"
require "active_support"

file1 = YAML::load(File.open('./en_20110207.yml'))
file2 = YAML::load(File.open('./locales/en.yml'))

arr = []

file1.select { |k,v|
  file2.select { |k2, v2|
    arr << "#{v2}" if "#{v}" != "#{v2}"
  }
}

puts arr

The output to the screen is the full file from file2. I know for a fact that the files are different, but the script doesn't seem to pick it up.

屏幕的输出是来自file2的完整文件。我知道这些文件是不同的，但是脚本似乎没有找到它。

11 个解决方案

#1

132

You can compare hashes directly for equality:

您可以直接将散列与等式进行比较:

hash1 = {'a' => 1, 'b' => 2}
hash2 = {'a' => 1, 'b' => 2}
hash3 = {'a' => 1, 'b' => 2, 'c' => 3}

hash1 == hash2 # => true
hash1 == hash3 # => false

hash1.to_a == hash2.to_a # => true
hash1.to_a == hash3.to_a # => false

You can convert the hashes to arrays, then get their difference:

可以将散列转换为数组，然后得到它们的差值:

hash3.to_a - hash1.to_a # => [["c", 3]]

if (hash3.size > hash1.size)
  difference = hash3.to_a - hash1.to_a
else
  difference = hash1.to_a - hash3.to_a
end
Hash[*difference.flatten] # => {"c"=>3}

Simplifying further:

进一步简化:

Assigning difference via a ternary structure:

通过三元结构分配差异:

  difference = (hash3.size > hash1.size) \
                ? hash3.to_a - hash1.to_a \
                : hash1.to_a - hash3.to_a
=> [["c", 3]]
  Hash[*difference.flatten] 
=> {"c"=>3}

Doing it all in one operation and getting rid of the difference variable:

在一次操作中完成所有操作，去掉差分变量:

  Hash[*(
  (hash3.size > hash1.size)    \
      ? hash3.to_a - hash1.to_a \
      : hash1.to_a - hash3.to_a
  ).flatten] 
=> {"c"=>3}

#2

You can try the hashdiff gem, which allows deep comparison of hashes and arrays in the hash.

您可以尝试hashdiff gem，它允许对散列中的散列和数组进行深入的比较。

The following is an example:

下面是一个例子:

a = {a:{x:2, y:3, z:4}, b:{x:3, z:45}}
b = {a:{y:3}, b:{y:3, z:30}}

diff = HashDiff.diff(a, b)
diff.should == [['-', 'a.x', 2], ['-', 'a.z', 4], ['-', 'b.x', 3], ['~', 'b.z', 45, 30], ['+', 'b.y', 3]]

#3

If you want to get what is the difference between two hashes, you can do this:

如果你想知道两个散列之间的区别，你可以这样做:

h1 = {:a => 20, :b => 10, :c => 44}
h2 = {:a => 2, :b => 10, :c => "44"}
result = {}
h1.each {|k, v| result[k] = h2[k] if h2[k] != v }
p result #=> {:a => 2, :c => "44"}

#4

Rails is deprecating the diff method.

Rails不赞成diff方法。

For a quick one-liner:

快速一行程序:

hash1.to_s == hash2.to_s

#5

You could use a simple array intersection, this way you can know what differs in each hash.

您可以使用一个简单的数组交集，这样您就可以知道每个散列的不同之处。

    hash1 = { a: 1 , b: 2 }
    hash2 = { a: 2 , b: 2 }

    overlapping_elements = hash1.to_a & hash2.to_a

    exclusive_elements_from_hash1 = hash1.to_a - overlapping_elements
    exclusive_elements_from_hash2 = hash2.to_a - overlapping_elements

#6

This was answered in "Comparing ruby hashes". Rails adds a diff method to hashes. It works well.

这在“比较ruby散列”中得到了回答。Rails向散列添加了一个diff方法。它的工作原理。

#7

I had the same problem and sent a pull request to rails

我遇到了同样的问题，并向rails发送了一个拉请求

Works with deeply nested hash
使用深度嵌套散列
Works with arrays of hashes
处理哈希数组

https://github.com/elfassy/rails/commit/5f3410e04fe8c4d4745397db866c9633b80ccec6

#8

If you need a quick and dirty diff between hashes which correctly supports nil in values you can use something like

如果您需要在正确支持nil值的散列之间快速而肮脏的差值，可以使用类似的方法

def diff(one, other)
  (one.keys + other.keys).uniq.inject({}) do |memo, key|
    unless one.key?(key) && other.key?(key) && one[key] == other[key]
      memo[key] = [one.key?(key) ? one[key] : :_no_key, other.key?(key) ? other[key] : :_no_key]
    end
    memo
  end
end

#9

If you want a nicely formatted diff, you can do this:

如果您想要一个格式良好的diff，您可以这样做:

# Gemfile
gem 'awesome_print' # or gem install awesome_print

And in your code:

和在你的代码:

require 'ap'

def my_diff(a, b)
  as = a.ai(plain: true).split("\n").map(&:strip)
  bs = b.ai(plain: true).split("\n").map(&:strip)
  ((as - bs) + (bs - as)).join("\n")
end

puts my_diff({foo: :bar, nested: {val1: 1, val2: 2}, end: :v},
             {foo: :bar, n2: {nested: {val1: 1, val2: 3}}, end: :v})

The idea is to use awesome print to format, and diff the output. The diff won't be exact, but it is useful for debugging purposes.

我们的想法是使用很棒的打印来格式化，并减少输出。这个差异不会很精确，但是对于调试很有用。

#10

... and now in module form to be applied to a variety of collection classes (Hash among them). It's not a deep inspection, but it's simple.

…现在以模块形式应用于各种集合类(其中哈希)。这不是深入的检查，但很简单。

# Enable "diffing" and two-way transformations between collection objects
module Diffable
  # Calculates the changes required to transform self to the given collection.
  # @param b [Enumerable] The other collection object
  # @return [Array] The Diff: A two-element change set representing items to exclude and items to include
  def diff( b )
    a, b = to_a, b.to_a
    [a - b, b - a]
  end

  # Consume return value of Diffable#diff to produce a collection equal to the one used to produce the given diff.
  # @param to_drop [Enumerable] items to exclude from the target collection
  # @param to_add  [Enumerable] items to include in the target collection
  # @return [Array] New transformed collection equal to the one used to create the given change set
  def apply_diff( to_drop, to_add )
    to_a - to_drop + to_add
  end
end

if __FILE__ == $0
  # Demo: Hashes with overlapping keys and somewhat random values.
  Hash.send :include, Diffable
  rng = Random.new
  a = (:a..:q).to_a.reduce(Hash[]){|h,k| h.merge! Hash[k, rng.rand(2)] }
  b = (:i..:z).to_a.reduce(Hash[]){|h,k| h.merge! Hash[k, rng.rand(2)] }
  raise unless a == Hash[ b.apply_diff(*b.diff(a)) ] # change b to a
  raise unless b == Hash[ a.apply_diff(*a.diff(b)) ] # change a to b
  raise unless a == Hash[ a.apply_diff(*a.diff(a)) ] # change a to a
  raise unless b == Hash[ b.apply_diff(*b.diff(b)) ] # change b to b
end

#11

-3

How about another, simpler approach:

另一种更简单的方法呢?

require 'fileutils'
FileUtils.cmp(file1, file2)

#1

132