[英]What is the most idiomatic Ruby way to step through a hash, updating values at each step?
[英]What is an idiomatic way to update hash keys in Ruby?
遍歷哈希時,不能更改鍵。 假設您要向每個鍵添加“ _new”:
hash = { 'a' => 1, 'b' => 2 }
new_pairs = Hash.new
hash.each do | k,v |
new_pairs[ k + '_new' ] = v
hash.delete k
end
hash.merge! new_pairs
有沒有更清潔,更慣用的紅寶石方式呢?
您不需要就地突變( merge!
)。 我會做這樣的事情:
hash = { 'a' => 1, 'b' => 2 }
hash2 = Hash[hash.map{|k, v| [k + '_new', v] }]
hash2 # => {"a_new"=>1, "b_new"=>2}
您不能在修改哈希時直接迭代哈希,但可以在keys
迭代。
hash.keys.each{|k| hash["#{k}_new"] = hash.delete(k)}
隨便你!
hash = hash.keys.reduce({}) {|h,k| h[k + '_new'] = hash[k]; h}
hash.map { |k, v| {"#{k}_new" => v} }.reduce(:merge)
我會做如下:
hash = { 'a' => 1, 'b' => 2 }
nw_hash = Hash.new { |hsh, key| hsh[key+'_new'] = hash[key] }
hash.keys.each{|e| nw_hash[e] }
nw_hash
# => {"a_new"=>1, "b_new"=>2}
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