正则表达式与文本清洗：从半结构化文本提取字段

import re

LOG_PATTERN = re.compile(
    r"^(?P<date>\d{4}-\d{2}-\d{2}) "
    r"(?P<level>INFO|WARNING|ERROR) "
    r"user=(?P<user>[a-zA-Z0-9_-]+) "
    r"latency=(?P<latency>\d+)ms$"
)


def parse_log(line: str) -> dict[str, str | int] | None:
    match = LOG_PATTERN.fullmatch(line.strip())
    if match is None:
        return None
    data = match.groupdict()
    return {
        "date": data["date"],
        "level": data["level"],
        "user": data["user"],
        "latency_ms": int(data["latency"]),
    }


lines = [
    "2026-08-25 INFO user=alice latency=18ms",
    "invalid line",
]

for line in lines:
    print(parse_log(line))

secret = "token=abc123xyz"
print(re.sub(r"(?<=token=)[^\s]+", "***", secret))

import re

text = "ERROR id=12; WARNING id=37; ERROR id=51"
print(re.findall(r"(?:ERROR|WARNING) id=(\d+)", text))
print(re.split(r";\s*", text))

masked = re.sub(
    r"id=(\d+)",
    lambda match: f"id={'*' * len(match.group(1))}",
    text,
)
print(masked)