Question

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Modifying list while iterating

I have been given a task to make a code in python that will remove all members that occures more than once in a list and leave 1 copy of it.
Condition: it should be case-insesitive

So I’ve written down the following code:

string = raw_input()
list1 = string.split(",")
low_case_list = list1[:] #for case-insesitive
for i in range(len(low_case_list)):
    low_case_list[i] = low_case_list[i].lower()
for member in low_case_list:
    if(low_case_list.count(member) > 1):
        del list1[low_case_list.index(member)]
        del low_case_list[low_case_list.index(member)]

after the input I get this list: [a,b,c,d,A,B,C,D,a,b,c,d]
and after I do the operation on it: [B,D,a,b,c,d]

my question is, why it skips ‘B’ and ‘D’ when it removes the members?

Answer 1

Why not just convert your list into a set with all elements converted to lower-case, and then back to a list. You can use a generator for converting every element to lowercase.

You can do it like this: –

>>> l = ['a', 'b', 'c', 'A', 'B', 'C', 'a', 'b', 'c']
>>> new_list = list(set(elem.lower() for elem in l))
>>> new_list
['a', 'c', 'b']

Note that, order may be changed because, set does not maintain the order of it’s elements.