Python: How to use RegEx in an if statement?

Question

I have the following code which looks through the files in one directory and copies files that contain a certain string into another directory, but I am trying to use Regula

Answer 1

if re.search(r'pattern', string):

Simple if-test:

if re.search(r'ing\b', "seeking a great perhaps"):     # any words end with ing?
    print("yes")

Pattern check, extract a substring, case insensitive:

match_object = re.search(r'^OUGHT (.*) BE$', "ought to be", flags=re.IGNORECASE)
if match_object:
    assert "to" == match_object.group(1)     # what's between ought and be?

Notes:

• Use re.search() not re.match. Match restricts to the start of strings, a confusing convention if you ask me. If you do want a string-starting match, use caret or \A instead, re.search(r'^...', ...)

• Use raw string syntax r'pattern' for the first parameter. Otherwise you would need to double up backslashes, as in re.search('ing\\b', ...)

• In this example, \b is a special sequence meaning word-boundary in regex. Not to be confused with backspace.

• re.search() returns None if it doesn't find anything, which is always falsy.

• re.search() returns a Match object if it finds anything, which is always truthy.

• a group is what matched inside parentheses

• group numbering starts at 1

• Specs

• Tutorial