有while循环时替换列表的值

Question

So say I have ['habcuxabc929abc', 'tabc', 'q', 'jabcuabc9'] .

What I basically want to do is split each element in this list between the abc 's and count the remaining parts. So the list specified above would look like: [3, 1, 1, 3] . What I have done does that but the main thing I want to achieve is if this value is less than 2 then it removes all abc 's and replaces them with q 's. (This works so far, although it is probably not pythonic). If the value is greater than 2 then I just want it to remove the last 'abc' and replace it with q , leaving all the previous abc 's as they are but I don't know how to do this, any suggestions would be greatly appreciated.

while n < len(list123):
    dummylist = [len(r.split('abc')) for r in list123]

    if dummylist[n] <= 2:
        print 'true'
        list123 = [i.replace('abc',' q ') for i in list123]
        n=n+1
    elif dummylist[n] > 2:
        print 'false'
        list123 = [i.replace('abc',' q ') for i in list123]
        n=n+1

Thanks!

Answer 1

Firstly, a while loop is the wrong choice here, and having the split inside it seems ludicrous.

Secondly, you don't want to replace all of the items in list123 if any happen to have fewer than two parts; only modify list123[i] as you iterate over each index i .

Thirdly, to remove only the last 'abc' you can use str.rsplit and specify a maximum of one splits, then str.join back together with 'q' instead.

This is much neater:

dummylist = [len(r.split('abc')) for r in list123]
for i, n in enumerate(dummylist):
    if n <= 2:
        list123[i] = list123[i].replace('abc', 'q')
    else:
        list123[i] = 'q'.join(list123[i].rsplit('abc', 1))

This gives me list123 == ['habcuxabc929q', 'tq', 'q', 'jabcuq9'] .

Answer 2

If I understand you correctly, it looks like you want something close to:

lst = ['habcuxabc929abc', 'tabc', 'q', 'jabcuabc9']
for i in range(len(lst)):
    dummy_lst = lst[i].split('abc')
    if len(dummy_lst) <= 2:
        lst[i] = ' q '.join(dummy_lst)
    else:
        lst[i] = 'abc'.join(dummy_lst[:-1]) + ' q ' + dummy_lst[-1]
print(lst)