[Tutor] Error in apparently correct code

[Osemeka Osuagwu]

Dear Pythonistas (I hope you don't mind that),
I wrote the following code to find the four adjacent numbers (in any
direction in the array) which, when multiplied together, would yield the
highest product to be gotten. I finally stumbled on the answer while
studying the data itself but I'm still stumped as to why I keep getting an
error while running the code. I would like answers to this and also any
suggestions as to more elegant ways of solving this problem.

THE CODE

data = [[ 8, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12,
50, 77, 91, 8],

[49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56,
62, 00],

[81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13,
36, 65],

[52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02,
36, 91],

[22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33,
13, 80],

[24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17,
12, 50],

[32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38,
64, 70],

[67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94,
21],

[24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89,
63, 72],

[21, 36, 23, 9, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33,
95],

[78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 9, 53, 56,
92],

[16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29,
85, 57],

[86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54,
17, 58],

[19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89,
55, 40],

[04, 52, 8, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98,
66],

[88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93,
53, 69],

[04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76,
36],

[20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04,
36, 16],

[20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,
05, 54],

[01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19,
67, 48]]


def down_right_product(row, col):

if (row>len(data)-3) or (col>len(data[row])-3):

return 1

else:

return reduce(lambda x,y:x*y, [data[row+each][col+each] for each in
range(4)])


def down_left_product(row, col):

if (row>len(data)-3) or (col<3):

return 1

else:

return reduce(lambda x,y:x*y, [data[row-each][col-each] for each in
range(4)])


def right_product(row, col):

if col>len(data[row])-3:

return 0

else:

return reduce(lambda x,y:x*y, [data[row][i] for i in range(col, col+4)])


def down_product(row, col):

if row>len(data)-3:

return 1

else:

return reduce(lambda x,y:x*y, [data[i][col] for i in range(row, row+4)])



def main():

prod = 1

source = []

for row in range(len(data)):

for col in range(len(data[row])):

if right_product(row, col) > prod:

prod = right_product(row, col)

source = [data[row][i] for i in range(col, col+4)]

if down_product(row, col) > prod:

prod = down_product(row, col)

source = [data[i][col] for i in range(row, row+4)]

if down_right_product(row, col) > prod:

prod = down_right_product(row, col)

source = [data[row+each][col+each] for each in range(4)]

if down_left_product(row, col) > prod:

prod = down_left_product(row, col)

source = [data[row-each][col-each] for each in range(4)]

print 'Maximum product is %d from %l' %(prod, source)


if __name__ == '__main__':

main()




THE ERROR


Traceback (most recent call last):

  File "C:\Windows.old\Users\Abasiemeka\Abasiemeka\GOOGLE
University\Python\Python Code\MyCode\Project Euler code\Project Euler
answer 11.py", line 84, in <module>

    main()

  File "C:\Windows.old\Users\Abasiemeka\Abasiemeka\GOOGLE
University\Python\Python Code\MyCode\Project Euler code\Project Euler
answer 11.py", line 64, in main

    if right_product(row, col) > prod:

  File "C:\Windows.old\Users\Abasiemeka\Abasiemeka\GOOGLE
University\Python\Python Code\MyCode\Project Euler code\Project Euler
answer 11.py", line 49, in right_product

    return reduce(lambda x,y:x*y, [data[row][i] for i in range(col, col+4)])

IndexError: list index out of range


p.s I apologise for the lack of comments

Regards,

Abasiemeka
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