Question

Can anyone help me understand why this works…

z = re.findall(r'(foobar)', string)

But this doesn’t?

regexStr = "r'(foobar)'"
z = re.findall(regexStr, string)

I’ve printed regexStr and determined that it’s output is IDENTICAL to r'(foobar)’.

Can someone pls help? I’ve also tried escaping the apostrophes too.

JD

Answer 1

A solution to your problem is

regexStr = r'(%s)' % searchString

where searchString will replace %s

In Python it is often better to use this construct than regular concatenation. (meaning str1 + str2 + … )
Especially as you don’t have to care about converting ints doubles and so on.

More on the subject here: 3.5. Formatting Strings

The r should not be part of the string, it only tells the python interpreter what kind of string it is:

r('hello\n')  # Raw string => (hello\n)
u'unicodestring'