Ruby散列有点扁平化

Question

拥有这个哈希数组，：

a = [{"red"=>"130"}, {"blue"=>"94"}, {"green"=>"57"}]

我希望像这样得到一个完整的扁平哈希：

{"red"=>"130", "blue"=>"94", "green"=>"57"}

Answer 1

[{"red"=>"130"}, {"blue"=>"94"}, {"green"=>"57"}].reduce(:merge)
# => {"red"=>"130", "blue"=>"94", "green"=>"57"} 

注意：

1. 将为空数组返回nil
2. 两者：Enumerable#reduce和Enumerable#inject都可以使用

Answer 2

使用Enumerable#inject和Hash#merge：

a = [{"red"=>"130"}, {"blue"=>"94"}, {"green"=>"57"}]
a.inject(:merge)
# => {"red"=>"130", "blue"=>"94", "green"=>"57"}

注意如果数组为空，则返回nil。

a = []
a.inject(:merge)  # <---
# => nil
a.inject({}, :merge)
# => {}

Answer 3

使用each_with_object(obj)的另一种方式：

a = [{"red"=>"130"}, {"blue"=>"94"}, {"green"=>"57"}]
a.each_with_object({}) { |h, o| o[h.keys.first] = h.values.first }
{"red"=>"130", "blue"=>"94", "green"=>"57"}

如果数组为空，则返回空哈希{}。

Answer 4

Hash[*a.map(&:to_a).flatten]
# => {"red"=>"130", "blue"=>"94", "green"=>"57"}

为空数组返回空哈希

Hash[*[].map(&:to_a).flatten]
# => {}