格式化“is_a？Integer”的正确方法是什么？

Question

我正在尝试使用下面的代码仅在密钥是整数时才在哈希中保留值。我在这里做错了什么？

hackerrank.keep_if do |x,y| x.is_a? Integer end

编辑：我必须做错事，因为我一直在HackerRank.com上遇到运行时错误。我的完整代码如下：

hackerrank.store[543121,100] # store new key-value pair
hackerrank.keep_if { |x,y| x.is_a?(Integer) } # keep if key is an integer
hackerrank.delete_if { |x,y| x % 2 == 0 } # delete if key is even

编辑2：此处提供了与挑战的链接：https://www.hackerrank.com/challenges/ruby-hash-add-del-sel

Answer 1

它需要看起来像这样（括号，而不是方括号）：

hackerrank.store(543121, 100)
#=> 100 

Answer 2

尝试 -

    hackerrank[543121] = 100 # store new key-value pair
    hackerrank.keep_if { |x,y| x.is_a?(Integer) && x.odd? } # keep if key is an integer and not even

或者使用@ seph的建议https://stackoverflow.com/a/31018495/2545197尝试使用您的代码 -

 hackerrank.store(543121,100) # store new key-value pair
 hackerrank.keep_if { |x,y| x.is_a?(Integer) } # keep if key is an integer
 hackerrank.delete_if { |x,y| x % 2 == 0 } # delete if key is even

Answer 3

# store expects two parameters, let‘s
#                ⇓ splat an array
hackerrank.store *[543121, 100]
# let’s select everything we are interested in
#        inplace ⇓     only integers ⇓⇓⇓  odds  ⇓⇓⇓⇓
hackerrank.select! { |(k,v)| Integer === k && k.odd? }