findall() 在 Python REGEX 中的 html 文件上返回空字符串

Question

I am learning Regex with Python and I am doing the baby names exercise of the Google Tutorial on Regex. The html file --baby1990.html-- is in a zipped file that can be downloaded here: https://developers.google.com/edu/python/set-up ('Download Google Python Exercises')

The year is placed within Tags. The html code is the following:

<h3 align="center">Popularity in 1990</h3>

I am using the following code to extract the year from the file:

f = open('C:/Users/ALEX/MyFiles/JUPYTER NOTEBOOKS/google-python-exercises/babynames/baby1990.html', 'r')

strings = re.findall(r'<h3 align="center">Popularity in (/d/d/d/d)</h3>', f.read())

I have tested the pattern with RegularExpressions101 website and it works.

However the 'strings' list returned is empty.

len(strings) out

Answer 1

I think the best way to match a year in a contextual string is to use re.search or re.match .

For instance:

import re

tag = """<h3 align="center">Popularity in 1990</h3>"""

mo = re.search(r"Popularity in (\d{4})", tag)
year = mo.group(1) if mo else ""

print(year)
# -> 1990

Or course, if you want to find all matches, you need to use re.findall …

You check your Python RegEx, you can also try online with https://regex101.com/