CODEWITHSUNDEEP
pythonlist2d
Jason
Jason

Reputation: 7

Need help checking input for 2D matrix with python

I need to find how to check if the input, which is a list, is 2D with the same amount of columns as rows and the same amount of parts in them. Example: [[4,5],[4,5,6]] and [[2,3],[6,1],[2,9]] would generate error messages. But [[3,4,5],[4,6,8],[5,8,-1]] and [[4,5],[4,1]] would be correct. I have tried:

    for row in square:
        if len(row) != len(square):
            return False

but that doesn't work quite right.

EDIT: Also this check is at the start of a list of checks, so it need to be in a if statement format.

Upvotes: 0

Views: 1395

Answers (2)

Pines
Pines

Reputation: 396

Is there a return value if the test is not failed? Putting your code in a function, assuming there's nothing more to the test:

def matrix_test(square):
    for row in square:
        if len(row) != len(square):
             return False

...either returns False or doesn't return a value returns None. So if you test a matrix by calling this function, you will never get a True result for the matrices that pass the test. So if it's not already there, add the final line:

    return True

You can then check a particular matrix with 

if matrix_test(matrix001):
    #run the next test

If that's not the problem it would help to see more of the code, and to know what happens when it runs.

Upvotes: 1

mgilson
mgilson

Reputation: 309851

Assuming your matrix is a sequence that holds other sequences (like a list of lists as you have in your question), you could simply do something like:

def is_square(matrix):
    return all(len(row) == len(matrix) for row in matrix)

Upvotes: 1

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