Create parameterized Python regular expression pattern

Question

I would like to create regular expression using re module. But it's unclear how to create a pattern in the similar way of creating a formatted string, e.g.: I need something like

myPattern = r'\s*{linehead}'.format(someText)

Is this possible?

When I use

if myPattern.search(l) is not None:,

I'm getting

AttributeError: 'str' object has no attribute 'search'

Yes, but you need to use a keyword argument for this pattern: myPattern = r'\s*{linehead}'.format(linehead="someText") — Brionius
– Brionius, Commented Mar 14, 2015 at 19:18
When I use if myPattern.search(l) is not None:, I'm getting AttributeError: 'str' object has no attribute 'search' — kakyo
– kakyo, Commented Mar 14, 2015 at 19:26
or myPattern = re.compile(r'\s*{linehead}'.format(linehead="someText"); myPattern.search(l) is not None — IceArdor
– IceArdor, Commented Mar 14, 2015 at 19:31

Jacob Schaer · Accepted Answer · 2015-03-14 20:16:14Z

2

As was mentioned in the comments, myPattern is simply a string. The 'r' simply tells Python that it's a "raw" string and shouldn't attempt to interpret escaped text.

Once you have your regular expression formatted the way you like it (note, since you named the parameter "linhead", you'll need to identify it in the arguments to format:

myPattern = r'\s*{linehead}'.format(linehead="someText")

You need to make an regular expression object with re.compile().

myRegex = re.compile(myPattern)

You can now use myRegex as you originally intended:

if myRegex.search(l) is not None:
    ...

Or, you can do this all in one go as @IceArdor suggested:

myPattern = re.compile(r'\s*{linehead}'.format(linehead="someText");

See https://docs.python.org/2/library/re.html#module-re

answered Mar 14, 2015 at 20:16

Jacob Schaer

7371 gold badge9 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Create parameterized Python regular expression pattern

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related