Question

我有一个像这样的哈希数组，它按:a的值排序：

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

如何获取具有:a最小值的哈希值的此数组的子集？此处，:a的最小值为0，因此我需要：

[{: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

对我而言，似乎接受的答案假设数组中第一个元素的:a值是最小值。因此，如果在第一个元素中:a => 1处修改了数组，则结果不正确。这是一个例子：

# 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，没有做出这个假设我正在采取额外的步骤来找到:a的最小值

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}]

获得哈希的子阵

2 个答案: