Hashの初期値に配列を与える - Qiita

h = Hash.new { |h,k| h[k] = [] } p h # {} p h[:hoge] # [] h[:hoge] << "fuga" p h # { :hoge => ["fuga"] } Register as a new user and use Qiita more conveniently You get articles that match your needsYou can efficiently read back useful informationYou can use dark themeWhat you can do with signing up