I am trying to create a 'SuperList' class which is a list with a del_all() method. When I try to make it work with regexes, the del_all() method doesn't delete anything at all.
This is my current code:
import re
class SuperList(list):
def __init__(self, seq):
list.__init__(self, seq)
self.seq = list(seq)
def del_all(self, item="", regex=None):
if item not in self.seq:
if not regex:
raise ValueError("item not in list")
else:
for i in range(len(self.seq)):
if re.match(re.compile(regex), self.seq[i]):
self.seq.remove(self.seq[i])
else:
if not regex:
while item in self.seq:
self.seq.remove(item)
else:
for i in range(len(self.seq)):
if re.match(regex, self.seq[i]):
self.seq.remove(self.seq[i])
super_list = SuperList(["A", "b", "f", "Y"])
super_list.del_all(regex=re.compile("[A-Z]]"))
print(super_list.seq)
The expected output here is ["b", "f"]. But instead I get ["A", "b", "f", "Y"]. How can I fix my code?
This pattern [A-Z]] will not match any of the items in the list. It matches an uppercase char A-Z followed by an ]
If you change the pattern to [a-z] to match a lowercase char, the code has a match.
But, in this part of the code you are removing the item in the list that you are iterating which might give you an error:
IndexError: list index out of range
For this part of the code
for i in range(len(self.seq)):
if re.match(regex, self.seq[i]):
self.seq.remove(self.seq[i])
What you might do, is not unset the index, but filter the seq using a for comprehension instead;
self.seq = [x for x in self.seq if re.match(regex, x)]
Output
['b', 'f']
Then you might also take that same approach for the last part of the code where you use remove