在python中使用正则表达式匹配文件名

Question

I'm looking for a regex command to match file names in a folder. I already got all the filenames in a list. Now I want to match a pattern in a loop (file is the string to match):

./test1_word1_1.1_1.2_1.3.csv

with:

match = re.search(r'./{([\w]+)}_word1_{([0-9.]+)}_{([0-9.]+)}_{([0-9.]+)}*',file)

I used to get regex working but in this special case it simple doesn't work. Can you help me with that?

I want to continue with the match of regex the following way (I've written the outcome here):

match[0] = test1
match[1] = 1.1
match[2] = 1.2
match[3] = 1.3

The curly brackets are my fault. They don't make sense at all. Sorry

Best regards, sebastian

Answer 1

You may use

r'\./([^\W_]+)_word1_([0-9.]+)_([0-9.]+)_([0-9]+(?:\.[0-9]+)*)'

See the regex demo

Details :

• \\. - a literal dot (if it is unescaped it matches any char other than a line break char)
• / - a / symbol (no need escaping it in a Python regex pattern)
• ([^\\W_]+) - Group 1 matching 1 or more letters or digits (if you want to match a chunk containing _ , keep your original (\\w+) pattern)
• _word1_ - a literal substring
• ([0-9.]+) - Group 1 matching 1 or more digits and/or . symbols
• _ - an underscore
• ([0-9.]+) - Group 2 matching 1 or more digits and/or . symbols
• _ - an underscore
• ([0-9]+(?:\\.[0-9]+)*) - Group 3 matching 1 or more digits, then 0+ sequences of a . and 1 or more digits

Python demo :

import re
rx = r"\./([^\W_]+)_word1_([0-9.]+)_([0-9.]+)_([0-9]+(?:\.[0-9]+)*)"
s = "./test1_word1_1.1_1.2_1.3.csv"
m = re.search(rx, s)
if m:
    print("Part1: {}\nPart2: {}\nPart3: {}\nPart4: {}".format(m.group(1), m.group(2), m.group(3), m.group(4) ))

Output:

Part1: test1
Part2: 1.1
Part3: 1.2
Part4: 1.3

Answer 2

Since test_word<>.csv is the file name and content inside <> will always changing and are dot delimited numbers, Can you try this?

r"test1_word[_0-9.]*.csv"g

Sample code and test strings

# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility

import re

regex = r"test1_word[_0-9.]*.csv"

test_str = ("./test1_word1_1.1_1.2_1.3.csv\n"
    "./test1_word1_1.31.2_1.555.csv\n"
    "./test1_word1_10.31.2_2000.00.csv")

matches = re.finditer(regex, test_str)

for matchNum, match in enumerate(matches):
    matchNum = matchNum + 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)))

# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

Want to test? https://regex101.com/ will help you.