CODEWITHSUNDEEP
python
beginner_user
beginner_user

Reputation: 109

find all possible rotation of a given string using python

Given string is "abc" then it should print out "abc", "bca", "cba"

My approach: find length of the given string and rotate them till length

def possible_rotation():
    a = "abc"
    b = len(a)
    for i in range (b-1):
        c = a[:i] + a[i:]
        print c

Above code simply prints abc, abc. Any idea what am I missing here?

Upvotes: 1

Views: 3195

Answers (7)

Amaury Liet
Amaury Liet

Reputation: 11163

Two things:

Firstly, as already pointed out in the comments, you should iterate over range(b) instead of range(b-1). In general, range(b) is equal to [0, 1, ..., b-1], so in your example that would be [0, 1, 2].

Secondly, you switched around the two terms, it should be: a[i:] + a[:i].

Upvotes: -1

shaddyshad
shaddyshad

Reputation: 217

This is what I did. I used a deque, A class in collections and then used the rotate function like this

from collections import deque

string = 'abc'

for i in range(len(string)):
    c = deque(string)
    c.rotate(i)
    print ''.join(list(c))

And gives me this output. 

abc
cab
bca

What it does. It creates a deque object, A double ended queue object, which has a method rotate, rotate takes the number of steps to rotate and returns the objects shifted to the right with the number of steps kinda like rshift in binary operations. Through the loops it shifts ad produces a deque object that I convert to list and finally to a string. Hope this helps

Upvotes: 1

boot-scootin
boot-scootin

Reputation: 12515

This looks to be homework, but here's a solution using the built-in collections.deque:

from collections import deque

def possible_rotations(string):
    rotated = deque(string)
    joined = None
    while joined != string:
        rotated.rotate(1)
        joined = ''.join(x for x in rotated)
        print(joined)

Test it out:

>>> print(possible_rotations('abc'))
cab
bca
abc

Upvotes: -1

Ravi Singh
Ravi Singh

Reputation: 93

No need to do (b-1),You simply do it by:

def possible_rotation():
    a = "abc"
    for i in range(0,len(a)):
         strng = a[i:]+a[:i]
         print strng
possible_rotation()

`

Upvotes: -1

corn3lius
corn3lius

Reputation: 4985

for i in range(b):
   print(a[i:] + a[:i])

0 - [a,b,c] + []
1 - [b,c]   + [a]
2 - [c ]    + [a,b]

swap the lists

Upvotes: 0

NPE
NPE

Reputation: 500167

You have two errors:

  • range(b-1) should be range(b);
  • a[:i] + a[i:] should be a[i:] + a[:i].

Upvotes: 2

vks
vks

Reputation: 67968

def possible_rotation():
    a = "abc"
    b = len(a)
    for i in range (b):
        c = a[i:]+a[:i]
        print c


possible_rotation()

Output:

abc bca cab

You have 2 issues.The range issue and the rotation logic.it should be a[i:]+a[:i] not the other way round.For range range(b-1) should be range(b)

Upvotes: 2

Related Questions