Finding whether a string starts with one of a list's variable-length prefixes

Question

I need to find out whether a name starts with any of a list\'s prefixes and then remove it, like:

if name[:2] in [\"i_\", \"c_\", \"m_\", \"l_\", \"d_\", \"t         


        

Answer 1

What about using filter?

prefs = ["i_", "c_", "m_", "l_", "d_", "t_", "e_", "b_"]
name = list(filter(lambda item: not any(item.startswith(prefix) for prefix in prefs), name))

Note that the comparison of each list item against the prefixes efficiently halts on the first match. This behaviour is guaranteed by the any function that returns as soon as it finds a True value, eg:

def gen():
    print("yielding False")
    yield False
    print("yielding True")
    yield True
    print("yielding False again")
    yield False

>>> any(gen()) # last two lines of gen() are not performed
yielding False
yielding True
True

Or, using re.match instead of startswith:

import re
patt = '|'.join(["i_", "c_", "m_", "l_", "d_", "t_", "e_", "b_"])
name = list(filter(lambda item: not re.match(patt, item), name))