Remove repeated letters from the string

Question

Would appreciate if anyone could provide a short method to remove the repeated letters.

Let's say I have a list of strings ['APPLE', 'BANANA']. I want to remove the repeated letters in the list items and the output maintain original order as ['APLE', 'BAN']. These are for n items in the list.

Please show us what you have already tried and where you are stuck. — Amit, Jan 07 '20 at 02:49
I have tried using iterators but two levels of for loops are taking time. Was looking for some shortcuts which I dont know. — Sumit Sharma, Jan 07 '20 at 02:52

score 0 · Answer 1 · answered Jan 07 '20 at 02:44

0

You can use a dictionary / array to store encountered letters in the word and for each such word, prepare a temporary string accordingly and in the end, push it in your result array.
Something like this :

final = []
for word in words:
    s = ''
    seen = {}
    for letter in word:
        if letter in seen:
            pass
        else:
            s += letter
            seen[letter] = True
    final.append(s)

answered Jan 07 '20 at 02:44

Uddeshya Singh

59
2
8

I want to avoid this iterator – Sumit Sharma Jan 07 '20 at 02:50

lenik · Answer 2 · 2020-01-07T03:14:25.253

0

This works, a simple oneliner that preserves the order:

>>> a = [ 'APPLE', 'GOOGLE', 'BANANA' ]
>>> [''.join( dict.fromkeys(i).keys() ) for i in a]
['APLE', 'GOLE', 'BAN']

edited Jan 07 '20 at 03:14

answered Jan 07 '20 at 02:54

lenik

23,228
4
34
43

Thank you this is exactly what I was looking for. Have you used the property of unique keys in a dictionary? Please explain for my understanding. Thank you – Sumit Sharma Jan 07 '20 at 03:15
@SumitSharma dicts are guaranteed to be ordered since python 3.something – lenik Jan 07 '20 at 03:17
Won't work for older versions of Python, to ensure code portability it's wiser to use an OrderedDict – Óscar López Jan 07 '20 at 03:18
@ÓscarLópez python 2 is dead already: "Python 2 End of Life Announced as January 1st 2020" – lenik Jan 07 '20 at 03:19
@SumitSharma and yes, keys are unique in `dict` – lenik Jan 07 '20 at 03:23
@lenik you'd be surprised to see how many projects still use old software versions. Better play it safe, just my two cents. – Óscar López Jan 07 '20 at 03:30

score 0 · Answer 3 · answered Jan 07 '20 at 03:02

0

words = ['APPLE', 'BANANA']
output = []

for word in words:
    seen = ''
    for char in word:
        if char not in seen:
            seen += char
    output.append(seen)
print(output)

answered Jan 07 '20 at 03:02

Bhosale Shrikant

463
3
7

Remove repeated letters from the string

3 Answers3