Ruby on Rails的 - 通过阵列，组哈希，并与多列

Question

我也有类似的问题，这个话题 Ruby on Rails - Hash of Arrays, group by and sum by column name

然而总和，我的问题是，通过和组具有很多列，而不是一个总和。

例如：我的哈希

[ 
    {"idx"=>"1234", "account"=>"abde", "money"=>"4.00", "money1"=>"1.00", "order"=>"00001", "order1"=>"1"}, 
    {"idx"=>"1235", "account"=>"abde", "money"=>"2.00", "money1"=>"1.00", "order"=>"00001", "order1"=>"1"}, 
    {"idx"=>"1235", "account"=>"abde", "money"=>"3.00", "money1"=>"1.00", "order"=>"00002", "order1"=>"2"} 
] 

结果这样

[ 
    {"idx"=>"1234", "account"=>"abde", "money"=>"6.00", "money1"=>"2.00","order"=>"00001", "order1"=>"1"}, 
    {"idx"=>"1234", "account"=>"abde", "money"=>"3.00", "money1"=>"1.00","order"=>"00002", "order1"=>"2"} 
] 

这样group_hashes arr, ["order","order1"], ["money","money1"]

我试图在一个循环内合并一个电话！但是，结果是错误的。 请教我解决这个案子。对不起，我的愚蠢头脑。

Answer 1

usnig Enumerable#group_by，您可以迭代由order,order1键组成的散列数组。

然后合并哈希（通过总结money，money1项）：

a = [ 
    {"idx"=>"1234", "account"=>"abde", "money"=>"4.00", "money1"=>"1.00", "order"=>"00001", "order1"=>"1"}, 
    {"idx"=>"1235", "account"=>"abde", "money"=>"2.00", "money1"=>"1.00", "order"=>"00001", "order1"=>"1"}, 
    {"idx"=>"1235", "account"=>"abde", "money"=>"3.00", "money1"=>"1.00", "order"=>"00002", "order1"=>"2"} 
] 
a.group_by { |x| x.values_at('order', 'order1') }.map {|key, hashes| 
    result = hashes[0].clone 
    ['money', 'money1'].each { |key| 
    result[key] = hashes.inject(0) { |s, x| s + x[key].to_f } 
    } 
    result 
} 
# => [{"idx"=>"1234", "account"=>"abde", "money"=>6.0, "money1"=>2.0, "order"=>"00001", "order1"=>"1"}, 
#  {"idx"=>"1235", "account"=>"abde", "money"=>3.0, "money1"=>1.0, "order"=>"00002", "order1"=>"2"}] 

---

group_keys = ['order', 'order1'] 
sum_keys = ['money', 'money1'] 
a.group_by { |x| x.values_at(*group_keys) }.map {|key, hashes| 
    result = hashes[0].clone 
    sum_keys.each { |key| 
    result[key] = hashes.inject(0) { |s, x| s + x[key].to_f } 
    } 
    result 
}