Python/matrix/spiral_print.py

"""
This program print the matrix in spiral form.
This problem has been solved through recursive way.

      Matrix must satisfy below conditions
        i) matrix should be only one or two dimensional
        ii)column of all the row should be equal
"""


def checkMatrix(a):
    # must be
    if type(a) == list and len(a) > 0:
        if type(a[0]) == list:
            prevLen = 0
            for i in a:
                if prevLen == 0:
                    prevLen = len(i)
                    result = True
                elif prevLen == len(i):
                    result = True
                else:
                    result = False
        else:
            result = True
    else:
        result = False
    return result


def spiralPrint(a):

    if checkMatrix(a) and len(a) > 0:

        matRow = len(a)
        if type(a[0]) == list:
            matCol = len(a[0])
        else:
            for dat in a:
                print(dat),
            return

        # horizotal printing increasing
        for i in range(0, matCol):
            print(a[0][i]),
        # vertical printing down
        for i in range(1, matRow):
            print(a[i][matCol - 1]),
        # horizotal printing decreasing
        if matRow > 1:
            for i in range(matCol - 2, -1, -1):
                print(a[matRow - 1][i]),
        # vertical printing up
        for i in range(matRow - 2, 0, -1):
            print(a[i][0]),
        remainMat = [row[1 : matCol - 1] for row in a[1 : matRow - 1]]
        if len(remainMat) > 0:
            spiralPrint(remainMat)
        else:
            return
    else:
        print("Not a valid matrix")
        return


# driver code
a = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
spiralPrint(a)