Rubyのメソッド内でputsを実行した場合と、メソッドを実行する際にputsをした場合の違い

Question

前提・実現したいこと

お世話になります。
あるwebサイトを、地域によってURLを変えながらRubyでMechanizeを用いてスクレイピングしたいと考えています。each文によってURLを変えていこうと考えたのですが、下記のようなコードではエラーが発生してしまいました。

def url(current_page)
  area = ["hokkaido?page=","aomori?page=","iwate?page=","miyagi?page=","akita?page=","yamagata?page=","fukushima?page=","ibaraki?page=","tochigi?page=","gunma?page=","saitama?page=","chiba?page=","tokyo?page=","kanagawa?page=","niigata?page=","yamanashi?page=","nagano?page=","toyama?page=","ishikawa?page=","fukui?page=","gifu?page=","shizuoka?page=","aichi?page=","mie?page=","shiga?page=","kyoto?page=","osaka?page=","hyogo?page=","nara?page=","wakayama?page=","tottori?page=","shimane?page=","okayama?page=","hiroshima?page=","yamaguchi?page=","tokushima?page=","kagawa?page=","ehime?page=","kochi?page=","fukuoka?page=","saga?page=","nagasaki?page=","kumamoto?page=","oita?page=","miyazaki?page=","kagoshima?page=","okinawa?page="]
  area.each do |a|
    "https://example/search/#{a}#{current_page}"
  end
end


name = []

(1..10).each do|i|
  page = agent.get(url(i))
  page.search('.name').each do |n|
    name << n
  end
  
  sleep 1
end

そこで問題を切り分けようと、

def a
  area = ["hokkaido?page=","aomori?page=","iwate?page=","miyagi?page=","akita?page=","yamagata?page=","fukushima?page=","ibaraki?page=","tochigi?page=","gunma?page=","saitama?page=","chiba?page=","tokyo?page=","kanagawa?page=","niigata?page=","yamanashi?page=","nagano?page=","toyama?page=","ishikawa?page=","fukui?page=","gifu?page=","shizuoka?page=","aichi?page=","mie?page=","shiga?page=","kyoto?page=","osaka?page=","hyogo?page=","nara?page=","wakayama?page=","tottori?page=","shimane?page=","okayama?page=","hiroshima?page=","yamaguchi?page=","tokushima?page=","kagawa?page=","ehime?page=","kochi?page=","fukuoka?page=","saga?page=","nagasaki?page=","kumamoto?page=","oita?page=","miyazaki?page=","kagoshima?page=","okinawa?page="]
  area.each do |a|
    "https://example/search/#{a}"
  end
end

としてコードを切り出し、ターミナルでputs aを実行してみたところ、"https://example/search/"が追加されず、"～～?page="の部分だけが出力されてしまいました。理由がわからず、下記のように、メソッドの中でputsを書いてメソッドを実行したところ、思い通りの結果が出力されました。
この理由がわかりません。
なぜ上記のコードでは"https://example/search/"が追加されず、下記のコードでは追加されるのでしょうか？

def a
  area = ["hokkaido?page=","aomori?page=","iwate?page=","miyagi?page=","akita?page=","yamagata?page=","fukushima?page=","ibaraki?page=","tochigi?page=","gunma?page=","saitama?page=","chiba?page=","tokyo?page=","kanagawa?page=","niigata?page=","yamanashi?page=","nagano?page=","toyama?page=","ishikawa?page=","fukui?page=","gifu?page=","shizuoka?page=","aichi?page=","mie?page=","shiga?page=","kyoto?page=","osaka?page=","hyogo?page=","nara?page=","wakayama?page=","tottori?page=","shimane?page=","okayama?page=","hiroshima?page=","yamaguchi?page=","tokushima?page=","kagawa?page=","ehime?page=","kochi?page=","fukuoka?page=","saga?page=","nagasaki?page=","kumamoto?page=","oita?page=","miyazaki?page=","kagoshima?page=","okinawa?page="]
  area.each do |a|
   　puts  "https://example/search/#{a}"
  end
end

発生している問題・エラーメッセージ

 absolute URL needed (not %5B%22hokkaido?page=%22,%20%22aomori?page=%22,%20%22iwate?page=%22,%20%22miyagi?page=%22,%20%22akita?page=%22,%20%22yamagata?page=%22,%20%22fukushima?page=%22,%20%22ibaraki?page=%22,%20%22tochigi?page=%22,%20%22gunma?page=%22,%20%22saitama?page=%22,%20%22chiba?page=%22,%20%22tokyo?page=%22,%20%22kanagawa?page=%22,%20%22niigata?page=%22,%20%22yamanashi?page=%22,%20%22nagano?page=%22,%20%22toyama?page=%22,%20%22ishikawa?page=%22,%20%22fukui?page=%22,%20%22gifu?page=%22,%20%22shizuoka?page=%22,%20%22aichi?page=%22,%20%22mie?page=%22,%20%22shiga?page=%22,%20%22kyoto?page=%22,%20%22osaka?page=%22,%20%22hyogo?page=%22,%20%22nara?page=%22,%20%22wakayama?page=%22,%20%22tottori?page=%22,%20%22shimane?page=%22,%20%22okayama?page=%22,%20%22hiroshima?page=%22,%20%22yamaguchi?page=%22,%20%22tokushima?page=%22,%20%22kagawa?page=%22,%20%22ehime?page=%22,%20%22kochi?page=%22,%20%22fukuoka?page=%22,%20%22saga?page=%22,%20%22nagasaki?page=%22,%20%22kumamoto?page=%22,%20%22oita?page=%22,%20%22miyazaki?page=%22,%20%22kagoshima?page=%22,%20%22okinawa?page=%22%5D) (ArgumentError)

該当のソースコード

def url(current_page)
  area = ["hokkaido?page=","aomori?page=","iwate?page=","miyagi?page=","akita?page=","yamagata?page=","fukushima?page=","ibaraki?page=","tochigi?page=","gunma?page=","saitama?page=","chiba?page=","tokyo?page=","kanagawa?page=","niigata?page=","yamanashi?page=","nagano?page=","toyama?page=","ishikawa?page=","fukui?page=","gifu?page=","shizuoka?page=","aichi?page=","mie?page=","shiga?page=","kyoto?page=","osaka?page=","hyogo?page=","nara?page=","wakayama?page=","tottori?page=","shimane?page=","okayama?page=","hiroshima?page=","yamaguchi?page=","tokushima?page=","kagawa?page=","ehime?page=","kochi?page=","fukuoka?page=","saga?page=","nagasaki?page=","kumamoto?page=","oita?page=","miyazaki?page=","kagoshima?page=","okinawa?page="]
  area.each do |a|
    "https://example/search/#{a}#{current_page}"
  end
end


name = []


(1..2).each do|i|
  page = agent.get(url(i))
  page.search('.name').each do |n|
    name << n
  end
  
  sleep 1
end

補足情報（FW/ツールのバージョンなど）

ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]

Answer 1

eachだからselfつまりarea = ["hokkaido?page=","aomori?page=",...]を返します

map(もしくはcollect)を使うと
["https://example/search/hokkaido?page="...]を返せます。

ただし、agent.getが配列に対応しているようには思いませんので

urls = url(i)
urls.each{|u|
  page = agent.get(u)

的な事をしなければいけません。

---

なお、適切に待ち時間を入れずに連続でアクセスして逮捕されても私は責任を持ちません。

Comments

[tttkkm]

返答遅くなってしまい申し訳ありません！ありがとうございます！mapを使えばよかったんですね！
わざわざ助言までありがとうございます、一応sleep　1を入れていたのですが、2にすることにしました！
最後にもしよろしければお聞かせ願いたいのですが、
urls = url(i)
urls.each{|u|
page = agent.get(u)

こちら、
url(i).each{|u|
page = agent.get(u)
でも動作するのではないかと思うのですが、asmさんのように記述されるのにはそちらの方がわかりやすく、バグが発生しづらいから、とか何かしらの理由があるのでしょうか？
ご教授いただければ幸いです。

[asm]

特に意味はないですよ。

強いていえば、何かを何かに変換する系のメソッドは一度
p urls = url(i)
等で確認したい…という程度です。

それも大抵の場合は開発が進むにつれ後者のメソッドチェインに書き直す事も多いです

[tttkkm]

ありがとうございます！
なるほど、確認のためだったんですね、疑問が解消されました。重ね重ねありがとうございました！