I was trying to make the string HELLO to OHELL in Python. But couldn't get any way to rotate it without working with loops. How to code for it in just 1-2 lines so that I could get the desired pattern?
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Possible duplicate of Reverse a string in Pythonkabanus– kabanus2018-02-04 11:01:19 +00:00Commented Feb 4, 2018 at 11:01
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2I think reverse is the wrong term here.Mike Müller– Mike Müller2018-02-04 11:08:50 +00:00Commented Feb 4, 2018 at 11:08
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5 Answers
Here is one way:
def rotate(strg, n):
return strg[n:] + strg[:n]
rotate('HELLO', -1) # 'OHELL'
Alternatively, collections.deque ("double-ended queue") is optimised for queue-related operations. It has a dedicated rotate() method:
from collections import deque
items = deque('HELLO')
items.rotate(1)
''.join(items) # 'OHELL'
1 Comment
Jean-François Fabre
I like that answer because it also works with empty strings.
You can slice and add strings:
>>> s = 'HELLO'
>>> s[-1] + s[:-1]
'OHELL'
This gives you the last character:
>>> s[-1]
'O'
and this everything but the last:
>>> s[:-1]
'HELL'
Finally, add them with +.
2 Comments
Ray
How should I do if the list is numbers? because I got error : unsupported operand type(s) for +: 'int' and 'list'
Mike Müller
This is for strings. Maybe you men a list of numbers
[1, 2, 3]? >>> L = [1, 2, 3] >>> L[-1:] + L[:-1] [3, 1, 2]Here is what I use to rotate strings in Python3:
To rotate left by n:
def leftShift(text,n):
return text[n:] + text[:n]
To rotate right by n:
def rightShift(text,n):
return text[-n:] + text[:-n]
Comments
Here is a simple way of looking at it...
s = 'HELLO'
for r in range(5):
print(s[r:] + s[:r])
HELLO
ELLOH
LLOHE
LOHEL
OHELL
Comments
I would agree with Mike Müller's answer:
s = 'HELLO'
s = s[-1] + s[:-1]
I would like to share another way of looking at s[:-1]
s[0:-1]
This means that it is starting from the start and including everything except for s[-1]. I hope this helped.
Comments
