合併重複的數組項

Question

我有散列的數組...

array = [ 
{ 
    'keyword' => 'A', 
    'total_value' => 50 
}, 
{ 
    'keyword' => 'B', 
    'total_value' => 25 
}, 
{ 
    'keyword' => 'C', 
    'total_value' => 40 
}, 
{ 
    'keyword' => 'A', 
    'total_value' => 10 
}, 
{ 
    'keyword' => 'C', 
    'total_value' => 15 
}] 

我需要用相同的keyword值鞏固哈希。通過整合，我的意思是結合total_values。例如，合併上述數組後，應該只有一個散列，其中'keyword' => 'A'與'total_value => 60

Answer 1

array = [ 
{ 
    'keyword' => 'A', 
    'total_value' => 50 
}, 
{ 
    'keyword' => 'B', 
    'total_value' => 25 
}, 
{ 
    'keyword' => 'C', 
    'total_value' => 40 
}, 
{ 
    'keyword' => 'A', 
    'total_value' => 10 
}, 
{ 
    'keyword' => 'C', 
    'total_value' => 15 
}] 

m = array.inject(Hash.new(0)) do |hs,i| 
    hs[i['keyword']] += i['total_value'] 
    hs 
end 
p m 

輸出：

{"A"=>60, "B"=>25, "C"=>55} 

By consolidate, I mean combine total_values. For example, after consolidation of the above array, there should only be one hash with 'keyword' => 'A' with a 'total_value => 60

這裏是如何可以做到：

m = array.each_with_object(Hash.new(0)) do |h,ob| 
    if h['keyword'] == 'A' 
     h['total_value'] += ob['total_value'] 
     ob.update(h) 
    end 
end 
p m 
#=> {"keyword"=>"A", "total_value"=>60} 

Answer 2

一個簡單的方法是在將項添加到集合時執行此操作。開始添加一個項目，檢查關鍵字是否存在。如果（a）它在那裏，那麼只需將新項目的total_value添加到其中。否則（b）向集合添加新項目。

Answer 3

array.group_by{|h| h["keyword"]} 
.map{|k, v| { 
    "keyword" => k, 
    "total_value" => v.map{|h| h["total_value"]}.inject(:+) 
}}