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

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")

最简单的方法是包含gem 'activesupport'(或gem 'active_support')。

然后,在你的课上你只需要

require 'active_support/core_ext/hash/slice'

然后打电话

params.slice(:choice1, :choice2, :choice3) # => {:choice1=>"Oh look, another one", :choice2=>"Even more strings", :choice3=>"But wait"}

我认为声明其他可能有bug的函数是不值得的,最好使用在过去几年里调整过的方法。

如果你使用rails并且你在一个单独的列表中有键,你可以使用*符号:

keys = [:foo, :bar]
hash1 = {foo: 1, bar:2, baz: 3}
hash2 = hash1.slice(*keys)
=> {foo: 1, bar:2}

正如其他答案所述,你也可以使用slice!修改哈希(并返回擦除的键/值)。

最简单的方法是包含gem 'activesupport'(或gem 'active_support')。

参数个数。切片(:choice1,:choice2,:choice3)

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))