ruby - 获取哈希子数组

Question

我有一个这样的哈希数组，按以下值排序:a：

[{:a=>0, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]

我怎样才能得到这个数组的一个子集，它的哈希值是最小值:a？在这里，最小值:a是0，所以我需要：

[{:a=>0, :b=>10}, {:a=>0, :b=>35}]

Answer 1

z = [{:a=>0, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]
z.select{|y| y[:a] == z.first[:a]}

Answer 2

在我看来，接受的答案似乎假设:a数组中第一个元素的值是最小值。因此，如果数组:a => 1在第一个元素的位置被修改，那么结果是不正确的。这是示例：

# original
z = [{:a=>0, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]
puts z.select{|y| y[:a] == z.first[:a]}.inspect
# => [{:a=>0, :b=>10}, {:a=>0, :b=>35}] the result is the expected one

# modified :a of first element
z = [{:a=>1, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]
puts z.select{|y| y[:a] == z.first[:a]}.inspect
# => [{:a=>1, :b=>10}, {:a=>1, :b=>20}] here result does not have min :a

现在，不做那个假设，我正在采取额外的步骤来找到最小值:a

z = [{:a=>0, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]
# find the min :a
m = z.map { |y| y[:a] }.min
puts z.select{|y| y[:a] == m}.inspect
# => [{:a=>0, :b=>10}, {:a=>0, :b=>35}]

# modified :a of first element
z = [{:a=>1, :b=>10}, {:a=>0, :b=>35}, {:a=>1, :b=>20}, {:a=>2, :b=>0}]
m = z.map { |y| y[:a] }.min
puts z.select{|y| y[:a] == m}.inspect
# => [{:a=>0, :b=>35}]