我有一个这样的散列:
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
我想要一个简单的方法来拒绝所有不是choice+int的键。可以是choice1，或者从choice1到choice10。它变化。
我如何用单词选择和后面的一个或多个数字来挑选键?
奖金:
将散列转换为以tab (\t)作为分隔符的字符串。我这样做了，但它花了几行代码。通常大师级的卢比手可以在一行或几行内完成。
当前回答
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
choices = params.select { |key, value| key.to_s[/^choice\d+/] }
#=> {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
其他回答
使用散列切片
{ a: 1, b: 2, c: 3, d: 4 }.slice(:a, :b)
# => {:a=>1, :b=>2}
# If you have an array of keys you want to limit to, you should splat them:
valid_keys = [:mass, :velocity, :time]
search(options.slice(*valid_keys))
与散列::选择:
params = params.select { |key, value| /^choice\d+$/.match(key.to_s) }
关于奖金问题:
If you have output from #select method like this (list of 2-element arrays): [[:choice1, "Oh look, another one"], [:choice2, "Even more strings"], [:choice3, "But wait"]] then simply take this result and execute: filtered_params.join("\t") # or if you want only values instead of pairs key-value filtered_params.map(&:last).join("\t") If you have output from #delete_if method like this (hash): {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"} then: filtered_params.to_a.join("\t") # or filtered_params.values.join("\t")
这是一条解决完整原始问题的直线:
params.select { |k,_| k[/choice/]}.values.join('\t')
但是上面的大多数解决方案都是使用slice或简单的regexp来解决需要提前知道键的情况。
下面是另一种适用于简单和更复杂用例的方法，它在运行时是可切换的
data = {}
matcher = ->(key,value) { COMPLEX LOGIC HERE }
data.select(&matcher)
现在，这不仅允许在匹配键或值时使用更复杂的逻辑，而且也更容易测试，并且可以在运行时交换匹配逻辑。
解决原问题:
def some_method(hash, matcher)
hash.select(&matcher).values.join('\t')
end
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
some_method(params, ->(k,_) { k[/choice/]}) # => "Oh look, another one\\tEven more strings\\tBut wait"
some_method(params, ->(_,v) { v[/string/]}) # => "Even more strings\\tThe last string"
params = { :irrelevant => "A String",
:choice1 => "Oh look, another one",
:choice2 => "Even more strings",
:choice3 => "But wait",
:irrelevant2 => "The last string" }
choices = params.select { |key, value| key.to_s[/^choice\d+/] }
#=> {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}
