Ruby：如何在哈希结构中过滤以获得<>“1”的所有键？

Question

I want to find some elegant way to achieve this. Maybe like follwing:

hash={"1"=>"1","2"=>"2"}
r=[]
hash.each do |k,v|
    if k!="1"
       r<<k
    end
end
puts r

Any better way to achieve this?

Answer 1

You can use "array difference":

hash.keys - ['1']
#=> ["2"]

Answer 2

puts r = hash.keys.select { |i| i != "1" }

Answer 3

Here's one way:

r = hash.select { |k,v,| k != "1" }
puts r

Hope this helps,
Ben

Answer 4

hash.reject{|k,v| k == "1"}

I like reject over select with a negative test because it's more readable. "Reject values where X == '1' is true" versus "collect values where x != '1' is true".