Question

我有一个像：

这样的数组

[[score, count], [score, count]]

我需要添加所有分数并除以所有计数：）

这是一个例子

[[10, 2], [5, 2]] : (10x2 + 5x2)/4 = 7.5

Answer 1

arr = [[10, 2], [5, 2]]
#=> [[10, 2], [5, 2]]

arr.reduce(0) { |acc,(x,y)| acc + x * y }.to_f /  arr.reduce(0) { |acc,(_,y)| acc + y }
#=> 7.5

Answer 2

ary = [[10, 2], [5, 2]]
total_score = ary.reduce(0) { |sum, (a, b)| sum + a * b }
total_count = ary.reduce(0) { |sum, a| sum + a.last }
avg = total_score/total_count.to_f

Answer 3

这使得一次通过数组。

arr = [[10, 2], [5, 2], [3, 4]]

tot, div = arr.reduce([0,0]) { |(tot, div), (score, count)|
             [tot + (score * count), div + count] }
  #=> [42, 8]
tot/div.to_f #=> 5.25

计算

tot => 0 + 10*2 + 5*2 + 3*4 => 42
div => 0 +   2  +  2  +  4  =>  8

Answer 4

ary = [[400, 5], [240, 4]]
total_score = ary.map{|a| a.first*a.last}.sum
total_count = ary.map(&:last).sum
avg = total_score/total_count.to_f

Answer 5

data.inject(0) { |score, (x, y)| score + x * y }.to_f / data.inject(0) { |count, (_, y)| count + y }

如何使用数组平均得分：[[得分，计数]，[得分，计数]]

5 个答案: