Question

我尝试搜索，但任何解决方案都不起作用。

我有这个哈希数组

[{:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>1}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>1}, {:smartphone=>"iPhone X - Apple", :votes=>1}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>1}, {:smartphone=>"iPhone X - Apple", :votes=>0}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>1}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>0}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>1}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>1}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}]

我想为每部智能手机总结选票</ p>

我尝试

results.group_by { |hash1| hash1[:smartphone] }.map do |_,v|
  v.inject do |ele_hash2,ele_hash1|
      puts ele_hash2
      puts ele_hash1
     ele_hash2.merge(ele_hash1) {|k,o,n| k == :vote ? o+n : o }
  end
end

但它让我回头

[{:smartphone=>"Galaxy Note 8 - Samsung", :votes=>0}, {:smartphone=>"ZenFone 4 Pro - Asus", :votes=>0}, {:smartphone=>"Xperia XZ1 - Sony", :votes=>0}, {:smartphone=>"Mate 10 Pro - Huawei", :votes=>0}, {:smartphone=>"V30 - LG", :votes=>0}, {:smartphone=>"One Plus 5T", :votes=>0}, {:smartphone=>"Pixel 2 XL - Google", :votes=>1}, {:smartphone=>"Nokia 8", :votes=>0}, {:smartphone=>"Z2 Force - Moto", :votes=>0}, {:smartphone=>"U11 - HTC", :votes=>0}, {:smartphone=>"iPhone X - Apple", :votes=>0}]

并且这不正确，例如Apple iPhone X有1票。为什么呢？

Answer 1

如果arr是您的哈希数组，则可以执行以下操作。

arr.each_with_object(Hash.new(0)) { |g,h| h[g[:smartphone]] += g[:votes] }
  #=> {"Galaxy Note 8 - Samsung"=>1, "ZenFone 4 Pro - Asus"=>1,
  #    "Xperia XZ1 - Sony"=>0, "Mate 10 Pro - Huawei"=>0, "V30 - LG"=>1,
  #    "One Plus 5T"=>0, "Pixel 2 XL - Google"=>1, "Nokia 8"=>0, 
  #    "Z2 Force - Moto"=>0, "U11 - HTC"=>1, "iPhone X - Apple"=>2}

Hash.new(0)创建一个默认值为零的哈希值（有时称为计算哈希值）。见Hash::new。这意味着如果如此定义的散列h没有键k，则h[k]将返回默认值，此处为零。（散列不会更改。）表达式h[g[:smartphone]] += g[:votes]扩展为

h[g[:smartphone]] = h[g[:smartphone]] + g[:votes]

如果数组中的散列g的键"iPhone X - Apple"的值为:smartphone，则上面的表达式变为

h["iPhone X - Apple"] = h["iPhone X - Apple"] + g[:votes]

第一次遇到"iPhone X - Apple" :smartphone的值g时，正在构建的哈希h没有密钥"iPhone X - Apple"。因此，在上面的等式右侧的h["iPhone X - Apple"]设置为等于默认值零，所以我们有

h["iPhone X - Apple"] = g[:votes]

下次g[:smartphone]被发现等于"iPhone X - Apple"时，相等权限右侧的h["iPhone X - Apple"]将等于g[:votes]，因此默认值将不适用。< / p>

Answer 2

input.
  group_by { |h| h[:smartphone] }.
  map { |k, v| [k, v.reduce(0) { |acc, h| acc + h[:votes] }] }.
  to_h
#⇒ {
#  "Galaxy Note 8 - Samsung" => 1,
#     "Mate 10 Pro - Huawei" => 0,
#                  "Nokia 8" => 0,
#              "One Plus 5T" => 0,
#      "Pixel 2 XL - Google" => 1,
#                "U11 - HTC" => 1,
#                 "V30 - LG" => 1,
#        "Xperia XZ1 - Sony" => 0,
#          "Z2 Force - Moto" => 0,
#     "ZenFone 4 Pro - Asus" => 1,
#         "iPhone X - Apple" => 2
# }

或者，为了获得您想要的确切结果：

input.
  group_by { |h| h[:smartphone] }.
  map do |k, v|
    {smartphone: k, votes: v.reduce(0) { |acc, h| acc + h[:votes] }}
  end

您的代码不起作用，因为在Hash#merge内你有一个拼写错误k == :vote应该阅读k == :votes。

求和数组中某些散列键的值

2 个答案: