CODEWITHSUNDEEP
pythonstring
Mx321
Mx321

Reputation: 31

Is there a way to remove the last character of a string in Python in O(1) time complexity?

Is there an easy way to remove the last character of a string in Python in O(1) time complexity? Would using string = string[:-1] be O(1)?

Upvotes: 2

Views: 2035

Answers (2)

Pavel Gomon
Pavel Gomon

Reputation: 213

Got some timing for you:

# Stright-forward
example_string = 'some medium string for examining the timing of 
different 
truncate methodes'
example_string = example_string[:-1]

# Stright-forward explicit
example_string = 'some medium string for examining the timing of 
different 
truncate methodes'
example_string = example_string[0:len(example_string)-1]

# Deleting last char
example_string = 'some medium string for examining the timing of 
different truncate methodes'
example_string = bytearray(example_string, encoding='utf-8')
del example_string[len(example_string)-1]
example_string = example_string.decode(encoding='utf-8')

# Creative way using replace (only valid if this word is unique in your string)
example_string = 'some medium string for examining the timing of different 
truncate methodes'
example_string = example_string.replace('methodes', "methode")

Using timeit to execute all the above:

>>> print(f'{timeit.timeit(stmt=test_code)}\tStright-forward')
0.03856031800387427 Stright-forward
>>> print(f'{timeit.timeit(stmt=test_code)}\tStright-forward explicit')
0.07093821599846706 Stright-forward explicit
>>> print(f'{timeit.timeit(stmt=test_code)}\tDeleting last char')
0.34045136597706005 Deleting last char
>>> print(f'{timeit.timeit(stmt=test_code)}\tCreative way using replace (only valid if this word is unique in your string)')
0.07177364896051586 Creative way using replace (only valid if this word is unique in your string)

Upvotes: 1

chepner
chepner

Reputation: 532023

No, because strings are immutable. The only thing you can do is create a modified copy of a str value, which means copying all the characters you don't want to remove. Any such operation is inherently a O(n) operation.

string[:-1] doesn't remove the last character; it copies all but the last character.

Upvotes: 5

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