Ruby 组合哈希中的元素

Question

我有一个看起来像这样的：

data = {abc -> [[date1, val1], [date2,val2]], def -> [[date1,val3], [date2,val4]]}

我想加入 abc 和 def 元素，所以它是这样的：

data = {join -> [[date1, val1+val3], [date2, val2+val4]] }

我该如何去做。请注意，哈希中还有其他不应修改的元素。

Answer 1

我假设 abc、def 和 join 实际上是符号。

a = Hash[data.delete(:abc)]  # extract data[:abc] and convert it to a Hash ("a")
b = Hash[data.delete(:def)]  # extract data[:def] and convert it to a Hash ("b")
data[:join] = a.map do |k,v| # iterate over one of the extracted Hashes
  [k, v + (b[k] || 0)]       # for each key, return a 2-item array with the key,
end                          #   and the sum of the values from "a" and "b"