检查散列映射中的键是否都在数组中

Question

说我有阵列a = ["a","b"] 和hashmap {"hello" => "world", "a" => "d"}

那将返回false，因为“hello”不在数组'a'中。

hashmap：{"a" => "hello", "a" => "world"}没问题。

有没有办法在不手动完成所有工作的情况下执行此操作？例如：查找hashmap键是否是数组的子集？

Answer 1

这将有效：

(hash.keys - a).empty?
# if returns true means all keys present in array.
# if returns false means all keys are not present in array.

Answer 2

尝试这样的事情：

keys = hashmap.keys
(keys - a).empty?

结果'keys - a'是空的 - 这意味着所有键都在数组中

Answer 3

你正在寻找这个

吗？

a = ["a","b"]
b = {"hello" => "world", "a" => "d"}

(a-b.keys).empty?