如何仅在 Python 正则表达式中保留捕获的组？

Question

Please accept my apology if this is a dumb question.

I want to make a regex expression that can make the two following changes in Python.

1. $12345.67890 to 12345.67
2. $12345 to 12345

What would be an appropriate regex expression to make both changes?

Thank you in advance.

Answer 1

We can try using re.sub here:

inp = "Here is a value $12345.67890 for replacement."
out = re.sub(r'\$(\d+(?:\.\d{1,2})?)\d*\b', '\\1', inp)
print(out)

This prints:

Here is a value 12345.67 for replacement.

Here is an explanation of the regex pattern:

\$                  match $
(                   capture what follows
    \d+             match one or more whole number digits
    (?:\.\d{1,2})?  then match an optional decimal component, with up to 2 digits
)                   close capture group (the output number you want)
\d*                 consume any remaining decimal digits, to remove them
\b                  until hitting a word boundary

Answer 2

in notepad++ style i would do something like find \$(\d+\.)(\d\d)\d+ Replace \1\2

hope that helps