使用正则表达式读取日志

Question

我有一个 .txt 文件，其中包含以下格式的请求日志：

time_namelookup: 0,121668 
time_connect: 0,460643 
time_pretransfer: 0,460755 
time_redirect: 0,000000 
time_starttransfer: 0,811697 
time_total: 0,811813 
-------------
time_namelookup: 0,121665 
time_connect: 0,460643 
time_pretransfer: 0,460355 
time_redirect: 0,000000 
time_starttransfer: 0,813697 
time_total: 0,811853 
-------------
time_namelookup: 0,121558 
time_connect: 0,463243 
time_pretransfer: 0,460755 
time_redirect: 0,000000 
time_starttransfer: 0,911697 
time_total: 0,811413 

我想为每个类别创建一个值列表，因此我认为正则表达式在这种情况下可能相关。

import re

'''
In this exmaple, I save only the 'time_namelookup' parameter
The same logic adapted for other parameters.
'''

namelookup = []
with open('shaghai_if_config_test.txt', 'r') as fh:
     for line in fh.readlines():
         number_match = re.match('([+-]?([0-9]*[,])?[0-9]+)',line)
         namelookup_match = re.match('^time_namelookup:', line)
         if namelookup_match and number_match:
             num = number_match.group(0)
             namelookup.append(num)
             continue

我发现这个逻辑非常复杂，因为我必须执行两个正则表达式匹配。此外，number_match 参数与行不匹配，而^time_namelookup: ([+-]?([0-9]*[,])?[0-9]+) 工作正常

我正在为所描述的程序寻找有经验的建议。任何建议表示赞赏。

Answer 1

我的猜测是你设计了一个很好的表达式，我们可能会稍微修改一下：

(time_(?:namelookup|connect|pretransfer|redirect|starttransfer|total))\s*:\s*([+-]?(?:\d*,)?\d+)

用re.findall测试：

import re

regex = r"(time_(?:namelookup|connect|pretransfer|redirect|starttransfer|total))\s*:\s*([+-]?(?:\d*,)?\d+)"

test_str = ("time_namelookup: 0,121668 \n"
    "time_connect: 0,460643 \n"
    "time_pretransfer: 0,460755 \n"
    "time_redirect: 0,000000 \n"
    "time_starttransfer: 0,811697 \n"
    "time_total: 0,811813 \n")

print(re.findall(regex, test_str))

输出

[('time_namelookup', '0,121668'), ('time_connect', '0,460643'), ('time_pretransfer', '0,460755'), ('time_redirect', '0,000000'), ('time_starttransfer', '0,811697'), ('time_total', '0,811813')]

用re.finditer测试：

import re

regex = r"(time_(?:namelookup|connect|pretransfer|redirect|starttransfer|total))\s*:\s*([+-]?(?:\d*,)?\d+)"

test_str = ("time_namelookup: 0,121668 \n"
    "time_connect: 0,460643 \n"
    "time_pretransfer: 0,460755 \n"
    "time_redirect: 0,000000 \n"
    "time_starttransfer: 0,811697 \n"
    "time_total: 0,811813 \n"
    "-------------\n"
    "time_namelookup: 0,121665 \n"
    "time_connect: 0,460643 \n"
    "time_pretransfer: 0,460355 \n"
    "time_redirect: 0,000000 \n"
    "time_starttransfer: 0,813697 \n"
    "time_total: 0,811853 \n"
    "-------------\n"
    "time_namelookup: 0,121558 \n"
    "time_connect: 0,463243 \n"
    "time_pretransfer: 0,460755 \n"
    "time_redirect: 0,000000 \n"
    "time_starttransfer: 0,911697 \n"
    "time_total: 0,811413 ")

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

for matchNum, match in enumerate(matches, start=1):

    print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group()))

    for groupNum in range(0, len(match.groups())):
        groupNum = groupNum + 1

        print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum)))

表达式在this demo 的右上方面板中进行了解释，如果您想探索/简化/修改它。

正则表达式电路

jex.im 可视化正则表达式：

Answer 2

您可以通过在捕获左侧的列表上循环来使其更容易：

import re

lst = ['time_namelookup', 'time_connect', 'time_pretransfer', 'time_redirect', 'time_starttransfer', 'time_total']

result = []
for x in lst:
    result.append(re.findall(f'{x}: (.*)', s))

print(result)

s 是您的文本文件数据。

Answer 3

您还可以将itertools.groupby 和str.split 应用于非正则表达式解决方案：

from itertools import groupby
data = [i.strip('\n') for i in open('filename.txt')]
new_data = [[a, list(b)] for a, b in groupby(data, key=lambda x:x.startswith('time'))]
results = [dict(i.split(': ') for i in b) for a, b in new_data if a]

输出：

[{'time_namelookup': '0,121668 ', 'time_connect': '0,460643 ', 'time_pretransfer': '0,460755 ', 'time_redirect': '0,000000 ', 'time_starttransfer': '0,811697 ', 'time_total': '0,811813 '}, 
 {'time_namelookup': '0,121665 ', 'time_connect': '0,460643 ', 'time_pretransfer': '0,460355 ', 'time_redirect': '0,000000 ', 'time_starttransfer': '0,813697 ', 'time_total': '0,811853 '}, 
 {'time_namelookup': '0,121558 ', 'time_connect': '0,463243 ', 'time_pretransfer': '0,460755 ', 'time_redirect': '0,000000 ', 'time_starttransfer': '0,911697 ', 'time_total': '0,811413 '}]

Answer 4

如果格式这么简单，这里还有一个想法 - 使用 CSV 解析器读取文件，使用冒号作为分隔符。示例：

import csv
import itertools
from pprint import pprint as print

file = 'log.txt'
with open(file) as fp:
    reader = csv.reader(fp, delimiter=':')
    # filter out delimiter lines
    rows = [r for r in reader if len(r) == 2]
    # group pairs by first element to a dict of lists
    grouped = {k: [x[1] for x in v] for k, v
               in itertools.groupby(sorted(rows), key=lambda x: x[0])}
    print(grouped)

会给你：

{'time_connect': [' 0.460643 ', ' 0.460643 ', ' 0.463243 '],
 'time_namelookup': [' 0.121558 ', ' 0.121665 ', ' 0.121668 '],
 'time_pretransfer': [' 0.460355 ', ' 0.460755 ', ' 0.460755 '],
 'time_redirect': [' 0.000000 ', ' 0.000000 ', ' 0.000000 '],
 'time_starttransfer': [' 0.811697 ', ' 0.813697 ', ' 0.911697 '],
 'time_total': [' 0.811413 ', ' 0.811813 ', ' 0.811853 ']}

如果您需要进一步处理，请在字典理解中进行，例如解析数字：

grouped = {k: [float(x[1].strip()) for x in v] for k, v
           in itertools.groupby(sorted(rows), key=lambda x: x[0])}

输出：

{'time_connect': [0.460643, 0.460643, 0.463243],
 'time_namelookup': [0.121558, 0.121665, 0.121668],
 'time_pretransfer': [0.460355, 0.460755, 0.460755],
 'time_redirect': [0.0, 0.0, 0.0],
 'time_starttransfer': [0.811697, 0.813697, 0.911697],
 'time_total': [0.811413, 0.811813, 0.811853]}

pandas

如果你身边有pandas，你可以用它来读取CSV格式的日志，这样可以省去解析和分组数据的麻烦。示例：

import pandas as pd
df = pd.read_csv('log.txt', delimiter=':', header=None, names=['Name', 'Num']).dropna().reset_index(drop=True)
print(df)

将输出解析后的数据并准备使用：

                  Name       Num
0      time_namelookup  0.121668
1         time_connect  0.460643
2     time_pretransfer  0.460755
3        time_redirect  0.000000
4   time_starttransfer  0.811697
5           time_total  0.811813
6      time_namelookup  0.121665
7         time_connect  0.460643
8     time_pretransfer  0.460355
9        time_redirect  0.000000
10  time_starttransfer  0.813697
11          time_total  0.811853
12     time_namelookup  0.121558
13        time_connect  0.463243
14    time_pretransfer  0.460755
15       time_redirect  0.000000
16  time_starttransfer  0.911697
17          time_total  0.811413

现在对数据做任何你想做的事情，例如重塑数据框以获得更结构化的视图：

df['chunk'] = df.index // df.Name.unique().size
print(df.pivot(values='Num', columns='Name', index='chunk'))

# Output:

Name   time_connect  time_namelookup  time_pretransfer  time_redirect  time_starttransfer  time_total
chunk                                                                                                
0          0.460643         0.121668          0.460755            0.0            0.811697    0.811813
1          0.460643         0.121665          0.460355            0.0            0.813697    0.811853
2          0.463243         0.121558          0.460755            0.0            0.911697    0.811413

计算选定时间的统计数据：

print(df[df.Name == 'time_total'].describe())

# Output:

            Num
count  3.000000
mean   0.811693
std    0.000243
min    0.811413
25%    0.811613
50%    0.811813
75%    0.811833
max    0.811853

等等