正規表現

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# 正規表現の基本
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import re
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# 文字列の検索
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text = "Hello, World!"
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pattern = r"World"
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match = re.search(pattern, text)
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print(match.group())  # World
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# 文字列の置換
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text = "Hello, World!"
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pattern = r"World"
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replacement = "Python"
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result = re.sub(pattern, replacement, text)
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print(result)  # Hello, Python!
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# メタ文字
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pattern = r"\d+"  # 数字1文字以上
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match = re.search(pattern, "123")
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print(match.group())  # 123

1
# 正規表現の高度な使い方
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import re
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# キャプチャグループ
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text = "John Doe"
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pattern = r"(\w+) (\w+)"
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match = re.search(pattern, text)
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print(match.group(1))  # John
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print(match.group(2))  # Doe
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# 量指定子
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pattern = r"a{2,4}"  # aが2〜4回
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match = re.search(pattern, "aaa")
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print(match.group())  # aaa
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# 先読みと後読み
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pattern = r"(?<=Hello)\w+"  # Helloの後の単語
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match = re.search(pattern, "Hello World")
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print(match.group())  # World