总和哈希

Question

阵列的价值这是我的数组

[{:amount=>10, :gl_acct_id=>1, :alt_amount=>20}, {:amount=>20, :gl_acct_id=>2 
, :alt_amount=>30}] 

我想导致

[{:amount => 30}] or {:amount = 30} 

任何想法？

Answer 1

您可以使用inject来计算所有金额。如果需要，您可以将结果放回散列。

arr = [{:amount=>10, :gl_acct_id=>1, :alt_amount=>20}, {:amount=>20, :gl_acct_id=>2, :alt_amount=>30}]  
amount = arr.inject(0) {|sum, hash| sum + hash[:amount]} #=> 30 
{:amount => amount} #=> {:amount => 30} 

Answer 2

这是做这件事：

a = {amount:10,gl_acct_id:1,alt_amount:20},{amount:20,gl_acct_id:2,alt_amount:30} 
a.map {|h| h[:amount] }.reduce(:+) 

不过，我得到的是你的对象模型有点欠缺的感觉。有了一个更好的对象模型，你可能能够做这样的事情：

a.map(&:amount).reduce(:+) 

甚至只是

a.sum 

注意，如@ sepp2k指出的那样，如果你想摆脱一个Hash，您需要再次将其包装在Hash中。

Answer 3

total=0 
arr = [{:amount=>10, :gl_acct_id=>1, :alt_amount=>20}, {:amount=>20, :gl_acct_id=>2, :alt_amount=>30}] 
arr.each {|x| total=total+x[:amount]} 
puts total 

Answer 4

array.map { |h| h[:amount] }.sum

Answer 5

[{ 
    :amount=>10, 
    :gl_acct_id=>1, 
    :alt_amount=>20 
},{ 
    :amount=>20, 
    :gl_acct_id=>2, 
    :alt_amount=>30 
}].sum { |t| t[:amount] } 

Answer 6

红宝石2.4.0具有Enumerable#sum方法。所以你可以做

arr.sum {|h| h[:amount] }