ruby - Ruby: 配列と文字列の各一致のインデックスを取得する

Question

次のような文字列の配列があります。

["Greater New York City Area", "Saudi Arabia", "Bahrain", "Greater New York City Area", "Toronto Canada Area", "Nigeria", "Toronto Canada Area", "United Arab Emirates", "Toronto Canada Area", "Egypt", "Egypt", "Bangladesh", "Gurgaon India", "United Arab Emirates", "New Delhi Area India", "Saudi Arabia", "United Arab Emirates", "United Arab Emirates", "Toronto Canada Area", "Pakistan", "New Delhi Area India", "New Delhi Area India", "United Arab Emirates", "Mumbai Area India", "New Delhi Area India"]

文字列「Greater New York City Area」をこの配列の各要素と照合し、各一致のインデックスを 含む別の配列を返そうとしています。

上記の例では、答えは [0,3] になります。

各要素を手動で繰り返すことでこれを行うことができますが、それは適切な方法ではないようです。

のようなものが必要ですが.find_all、値ではなくインデックスを返す必要があります。

Answer 1

これを試して：

a = ["Greater New York City Area", "Saudi Arabia", "Bahrain", "Greater New York City Area", "Toronto Canada Area", "Nigeria", "Toronto Canada Area", "United Arab Emirates", "Toronto Canada Area", "Egypt", "Egypt", "Bangladesh", "Gurgaon India", "United Arab Emirates", "New Delhi Area India", "Saudi Arabia", "United Arab Emirates", "United Arab Emirates", "Toronto Canada Area", "Pakistan", "New Delhi Area India", "New Delhi Area India", "United Arab Emirates", "Mumbai Area India", "New Delhi Area India"]

results_with_index = a.each_with_index.select { |i, idx| i =~ /Greater New York City Area/} # [["Greater New York City Area", 0], ["Greater New York City Area", 3]] 

results_with_index.map! { |i| i[1] } # [0,3]

Answer 2

「each_with_index」メソッドを使用します。