Question

我有一个包含多行的文本文件。我想在两行（++起始行和 - 退出行）之间检查特定行（调用xyz ...）。如果（调用xyz ...）行存在，那么它应该返回该行，如果不存在行，则应该返回NULL值。我想将结果存储到列表中。

示例文件：

++ start line 
22 15:36:53 
dog, cat, monkey, rat
calling xxxxx
animal already added
-- exiting line

上面的行块应添加调用xxxxx 列表。

++ start line 
12 12:56:34 
cat, camel, cow, dog    
animal already added
-- exiting line

在上面的块调用中，xyz缺失，因此它应该将NULL添加到列表

预期产出

calling xxxxx
NULL

Answer 1

您可以使用此正则表达式检查您提到的情况：

^\+\+(?=(?:(?!\-\-).)*\s+(calling[^\n]+)).*?\s+--

Observe how the regex works here

如果匹配，则将主叫行作为组1

示例来源（run here）：

import re

regex = r"(?:^\+\+(?=(?:(?!\-\-).)*\s+(calling[^\n]+)).*?\s+--)|(?:^\+\+(?=(?:(?!\-\-).)*\s+(?!calling[^\n]+)).*?\s+--)"

test_str = ("++ start line \n"
    "22 15:36:53 \n"
    "dog, cat, monkey, rat\n"
    "calling xxxxx\n"
    "animal already added\n"
    "-- exiting line\n\n\n"
    "++ start line \n"
    "12 12:56:34 \n"
    "cat, camel, cow, dog    \n"
    "animal already added\n"
    "-- exiting line\n\n"
    "++ start line \n"
    "12 12:56:34 \n"
    "cat, camel, cow, dog  \n"
    "calling pqr  \n"
    "animal already added\n"
    "-- exiting line\n\n")

matches = re.finditer(regex, test_str, re.DOTALL | re.MULTILINE)

for match in matches:
    print(match.group(1))

输出：

calling xxxxx
None
calling pqr

Answer 2

您可能希望使用多个模式，一个用于分隔块，另一个用于块中的搜索calling...。

块的表达式（参见a demo here）：

^\+\+ (?P<block>[\s\S]+?) ^--.+
calling...的表达式：

^calling.+

Python

import re
rx_block = re.compile(r'''
    ^\+\+
    (?P<block>[\s\S]+?)
    ^--.+''', re.MULTILINE | re.VERBOSE)

rx_calling = re.compile(r'''
    ^calling.+
    ''', re.MULTILINE | re.VERBOSE)

numbers = [number.group(0) if number else None
            for block in rx_block.finditer(your_string_here)
            for number in [rx_calling.search(block.group('block'))]]
print(numbers)

哪个收益

['calling xxxxx', None]

Answer 3

可以使用拆分功能获取子部件并检查它们：

outlist = []
with open("calling.txt", "r") as ff:
    lines = ff.read()
    records = lines.split("++ start line ")
    records = list(filter(lambda x: len(x)>0, records))
    for rec in records:
        found = False
        rows = rec.split("\n")
        for row in rows:
            if not found and row.startswith("calling"):
                outlist.append(row.split(" ")[1])
                found = True
        if not found: 
            outlist.append("NULL")

print(outlist)

输出：

['xxxxx', 'NULL', 'pqr']

检查Python中的空行

3 个答案: