遍歷數組

Question

的哈希我有以下幾點：

@products = { 
    2 => [ 
    #<Review id: 9, answer01: 3, score: 67, style_id: 2, consumer_id: 2, 
    branch_id: 2, business_id: 2> 
    ], 
    15 => [ 
    #<Review id: 10, answer01: 3, score: 67, style_id: 2, consumer_id: 2, 
    branch_id: 2, business_id: 2>, 
    #<Review id: 11, answer01: 3, score: 67, style_id: 2, consumer_id: 2, 
    branch_id: 2, business_id: 2> 
    ] 
} 

我要平均每個產品的散列鍵相關聯的所有評論的分數。我怎樣才能做到這一點？

Answer 1

是的，只需使用map來製作一個每個產品的分數的數組，然後取數組的平均值。

average_scores = {} 
@products.each_pair do |key, product| 
    scores = product.map{ |p| p.score } 
    sum = scores.inject(:+) # If you are using rails, you can also use scores.sum 
    average = sum.to_f/scores.size 
    average_scores[key] = average 
end 

Answer 2

要遍歷一個哈希：

hash = {} 
hash.each_pair do |key,value| 
    #code 
end 

遍歷數組：

arr=[] 
arr.each do |x| 
    #code 
end 

所以在陣列的哈希迭代（假設我們正在迭代中的每個點每個陣列在散列中）將如下完成：

hash = {} 
hash.each_pair do |key,val| 
    hash[key].each do |x| 
    #your code, for example adding into count and total inside program scope 
    end 
end 

Answer 3

感謝您的回答Shingetsu，我肯定會讚揚它。我無意中想出了自己的答案。

trimmed_hash = @products.sort.map{|k, v| [k, v.map{|a| a.score}]} 
trimmed_hash.map{|k, v| [k, v.inject(:+).to_f/v.length]}