Ruby:如何将变量设置为0,或者如果已经设置,则增加1

Question

我知道|| =运算符,但不要认为它会帮助我...尝试创建一个数组来计算对象数组中"类型"的数量.

array.each do |c|
  newarray[c.type] = newarray[c.type] ? newarray[c.type]+1 ? 0
end

有没有更优雅的方式来做到这一点？

Answer 1

types = Hash.new(-1) # It feels like this should be 0, but to be
                     # equivalent to your example it needs to be -1
array.each do |c|
  types[c.type] += 1
end

Answer 2

Array#fetch如果索引不存在,请使用可以提供默认值的方法:

array.each do |c|
  newarray[c.type] = newarray.fetch(c.type, -1) + 1
end