You don't need in-place mutations (merge!
). I'd do something like this:
hash = { 'a' => 1, 'b' => 2 }
hash2 = Hash[hash.map{|k, v| [k + '_new', v] }]
hash2 # => {"a_new"=>1, "b_new"=>2}
Вопрос
When iterating though a hash, keys cannot be changed. Suppose you want to add '_new' to each key:
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
Is there a cleaner, more idiomatic ruby-like way of doing this?
Решение
You don't need in-place mutations (merge!
). I'd do something like this:
hash = { 'a' => 1, 'b' => 2 }
hash2 = Hash[hash.map{|k, v| [k + '_new', v] }]
hash2 # => {"a_new"=>1, "b_new"=>2}
Другие советы
You cannot directly iterate though a hash while modifying it, but you can iterate over keys
.
hash.keys.each{|k| hash["#{k}_new"] = hash.delete(k)}
Take your pick!
hash = hash.keys.reduce({}) {|h,k| h[k + '_new'] = hash[k]; h}
hash.map { |k, v| {"#{k}_new" => v} }.reduce(:merge)
I would do as below :
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}