In Python, how do I rotate a matrix 90 degrees counterclockwise?

up vote
0
down vote

favorite

>>> def rotate_matrix( k: List[List[int]]):

    """

    For example, if I have:

    m = [[1,2,3],

         [2,3,3],

         [5,4,3]]

    rotate_matrix(m) should give me [[3,3,3],[2,3,4],[1,2,5]]. 

    """

Edit: Preferably without numpy.

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

I answered your question - using python only, as you asked. If you agree that my answer is correct and faithful to the intent of your question, then please accept and/or up vote it. Or, please let me know what else you need, I am happy to try to help you. Thank you
– DrM
Nov 14 at 14:53

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:46

I just copied the code from the answer and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:13

add a comment |

up vote
0
down vote

favorite

>>> def rotate_matrix( k: List[List[int]]):

    """

    For example, if I have:

    m = [[1,2,3],

         [2,3,3],

         [5,4,3]]

    rotate_matrix(m) should give me [[3,3,3],[2,3,4],[1,2,5]]. 

    """

Edit: Preferably without numpy.

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

I answered your question - using python only, as you asked. If you agree that my answer is correct and faithful to the intent of your question, then please accept and/or up vote it. Or, please let me know what else you need, I am happy to try to help you. Thank you
– DrM
Nov 14 at 14:53

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:46

I just copied the code from the answer and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:13

add a comment |

up vote
0
down vote

favorite

>>> def rotate_matrix( k: List[List[int]]):

    """

    For example, if I have:

    m = [[1,2,3],

         [2,3,3],

         [5,4,3]]

    rotate_matrix(m) should give me [[3,3,3],[2,3,4],[1,2,5]]. 

    """

Edit: Preferably without numpy.

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

>>> def rotate_matrix( k: List[List[int]]):

    """

    For example, if I have:

    m = [[1,2,3],

         [2,3,3],

         [5,4,3]]

    rotate_matrix(m) should give me [[3,3,3],[2,3,4],[1,2,5]]. 

    """

Edit: Preferably without numpy.

python

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

edited Nov 11 at 21:22

Yvette Colomb♦

19.9k1369107

asked Nov 11 at 16:34

user10634718

141

asked Nov 11 at 16:34

user10634718

141

asked Nov 11 at 16:34

user10634718

141

I answered your question - using python only, as you asked. If you agree that my answer is correct and faithful to the intent of your question, then please accept and/or up vote it. Or, please let me know what else you need, I am happy to try to help you. Thank you
– DrM
Nov 14 at 14:53

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:46

I just copied the code from the answer and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:13

add a comment |

I answered your question - using python only, as you asked. If you agree that my answer is correct and faithful to the intent of your question, then please accept and/or up vote it. Or, please let me know what else you need, I am happy to try to help you. Thank you
– DrM
Nov 14 at 14:53

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:46

I just copied the code from the answer and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:13

I answered your question - using python only, as you asked. If you agree that my answer is correct and faithful to the intent of your question, then please accept and/or up vote it. Or, please let me know what else you need, I am happy to try to help you. Thank you
– DrM
Nov 14 at 14:53

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:46

I just copied the code from the answer and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:13

add a comment |

2 Answers
2

active

oldest

votes

up vote
2
down vote

You could use the numpy function rot90

import numpy as np

m = np.array([[1,2,3],

         [2,3,3],

         [5,4,3]])



def rotate_matrix(mat):

    return np.rot90(mat)

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

add a comment |

up vote
1
down vote

Here is the counter clockwise matrix rotation as one line in pure python (i.e., without numpy):

new_matrix = [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

If you want to do this in a function, then

def rotate_matrix( m ):

    return [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

and either way, the result for

m = [ [1,2,3], [2,3,3], [5,4,3]]

[[3, 3, 3], [2, 3, 4], [1, 2, 5]]

Aside, if you want the usual transpose, then the simple one line pure python version is

[[m[j][i] for j in range(len(m))] for i in range(len(m[0]))]

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
2
down vote

You could use the numpy function rot90

import numpy as np

m = np.array([[1,2,3],

         [2,3,3],

         [5,4,3]])



def rotate_matrix(mat):

    return np.rot90(mat)

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

add a comment |

up vote
2
down vote

You could use the numpy function rot90

import numpy as np

m = np.array([[1,2,3],

         [2,3,3],

         [5,4,3]])



def rotate_matrix(mat):

    return np.rot90(mat)

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

add a comment |

up vote
2
down vote

You could use the numpy function rot90

import numpy as np

m = np.array([[1,2,3],

         [2,3,3],

         [5,4,3]])



def rotate_matrix(mat):

    return np.rot90(mat)

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

You could use the numpy function rot90

import numpy as np

m = np.array([[1,2,3],

         [2,3,3],

         [5,4,3]])



def rotate_matrix(mat):

    return np.rot90(mat)

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

answered Nov 11 at 16:40

Vikhyat Agarwal

420214

add a comment |

up vote
1
down vote

Here is the counter clockwise matrix rotation as one line in pure python (i.e., without numpy):

new_matrix = [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

If you want to do this in a function, then

def rotate_matrix( m ):

    return [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

and either way, the result for

m = [ [1,2,3], [2,3,3], [5,4,3]]

[[3, 3, 3], [2, 3, 4], [1, 2, 5]]

Aside, if you want the usual transpose, then the simple one line pure python version is

[[m[j][i] for j in range(len(m))] for i in range(len(m[0]))]

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

add a comment |

up vote
1
down vote

Here is the counter clockwise matrix rotation as one line in pure python (i.e., without numpy):

new_matrix = [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

If you want to do this in a function, then

def rotate_matrix( m ):

    return [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

and either way, the result for

m = [ [1,2,3], [2,3,3], [5,4,3]]

[[3, 3, 3], [2, 3, 4], [1, 2, 5]]

Aside, if you want the usual transpose, then the simple one line pure python version is

[[m[j][i] for j in range(len(m))] for i in range(len(m[0]))]

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

add a comment |

up vote
1
down vote

Here is the counter clockwise matrix rotation as one line in pure python (i.e., without numpy):

new_matrix = [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

If you want to do this in a function, then

def rotate_matrix( m ):

    return [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

and either way, the result for

m = [ [1,2,3], [2,3,3], [5,4,3]]

[[3, 3, 3], [2, 3, 4], [1, 2, 5]]

Aside, if you want the usual transpose, then the simple one line pure python version is

[[m[j][i] for j in range(len(m))] for i in range(len(m[0]))]

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

Here is the counter clockwise matrix rotation as one line in pure python (i.e., without numpy):

new_matrix = [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

If you want to do this in a function, then

def rotate_matrix( m ):

    return [[m[j][i] for j in range(len(m))] for i in range(len(m[0])-1,-1,-1)]

and either way, the result for

m = [ [1,2,3], [2,3,3], [5,4,3]]

[[3, 3, 3], [2, 3, 4], [1, 2, 5]]

Aside, if you want the usual transpose, then the simple one line pure python version is

[[m[j][i] for j in range(len(m))] for i in range(len(m[0]))]

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

edited Nov 12 at 13:01

answered Nov 11 at 16:55

DrM

944314

answered Nov 11 at 16:55

DrM

944314

answered Nov 11 at 16:55

DrM

944314

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

add a comment |

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

I've tried the code in python IDLE and for some reason, it's outputting the original matrix instead of rotating it. Can you please help?
– user10634718
Nov 15 at 12:45

I just copied the code from here and ran it, it is perfect. Please check that you are printing the right array in your code, c.f. print( new_matrix )
– DrM
Nov 15 at 13:11

add a comment |

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