在哈希中求和数组的值

Question

这是我的阵列

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

我想要结果

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

任何的想法？

Answer 1

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

Answer 2

您可以使用inject总和所有金额.然后,如果需要,可以将结果放回哈希值.

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 3

Ruby版本> = 2.4.0有一个Enumerable#sum方法.所以你可以做到

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

Answer 4

这是一种方法:

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(:+)

但是,我觉得你的对象模型有点缺乏.使用更好的对象模型,您可能会执行以下操作:

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

甚至只是

a.sum

请注意,正如@ sepp2k指出的那样,如果你想要出局Hash,你需要Hash再次将它包装起来.

Answer 5

为什么不拔呢？

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

ary.pluck(:amount).sum

# for more reliability
ary.pluck(:amount).compact.sum