Rotating a Matrix in Python

Rotating a matrix in python trick :

Let there be a matrix called "img" , and for instance say there is a flag "f" which will determine the type of rotation :

f = 0 --> Left Rotate

f = 1 --> Right Rotate

The method we will implement will work irrespective the size of the matrix and does not have any limiting constraints.

INPUT :

[ 10 30

20 40 ]

if flag f = 1 :

OUTPUT :

[ 20 10

40 30 ]

if flag f = 0 :

OUTPUT :

[ 30 40

10 20 ]

so to perform, the above process on a matrix of dimension n*m :

def rotator(img,f):

rot =[]

if f==1:

rot = zip(*img[::-1])

else:

rot = zip(*img[::-1])

rot = zip(*rot[::-1])

#what we did was we right rotated 3 times the matrix to get a left rotated matrix

return rot

so how does it work ?

we had img = [[10 30],[20 40 ]]

now lets say f = 1:

img[::-1] --> [[20,40],[10,30]]

*img[::-1] --> [20,40],[10,30]

zip(*img[::-1]) --> zip([20,40],

[10,30]) #so 20 and 10 are zipped together

#and 40 and 30 are zipped together

--> [[20,10]

,[40,30]]