Using generator to fill integer values in 2-D array

Question

I want to use the below code (am supposed to not use map(), for an online programming site as gives error on that of : TypeError: 'map' object is not subscriptable ):

arr[i][j] = [int(input("Input score").strip().split()[:l]) for j in range(n) for i in range(t)]

instead of the below working version:

for i in range(t):   
    for j in range(n):
        arr[i][j] = map(int, input("Input score").strip().split())[:l]

but the error is (assume so) based on providing a list instead of individual values, as stated below:

TypeError: int() argument must be a string or a number, not 'list'

Unable to find a solution by any alternate way, say convert rhs (of desired soln.) to a string in first step & then assign to lhs in the second step; as need assign to arr[i][j].

P.S. Need to make the solution use the individual and row-wise values of arr, as say need find row-wise sum of values or even individual values. The below code uses the row-wise arr values to fill up total.

for i in range(t): 
    for j in range(n):
        # Find sum of all scores row-wise 
        sum = 0
        for m in arr[i][j]:
            sum += m
        total[i][j] = sum

Stephen Rauch · Accepted Answer · 2019-02-20 02:01:09Z

2

You can map your nested for loops:

for i in range(t):   
    for j in range(n):
        arr[i][j] = map(int, input("Input score").strip().split())[:l]

to a list comprehension like:

arr = [map(int, input("Input score").strip().split())[:l] for i in range(t) for j in range(n)]

And without a map like:

arr = [[int(k) for k in input("Input score").strip().split())[:l]] 
       for i in range(t) for j in range(n)]

edited Feb 20, 2019 at 2:01

answered Feb 20, 2019 at 1:46

Stephen Rauch♦

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3 Comments

jiten Over a year ago

Sorry, did not mention that am not supposed to use map().

jiten Over a year ago

No, a geeksforgeeks site practice sample question, not even contest.

jiten Over a year ago

But need arr[i][j] to have row-wise sum of values. Please tell me how to use arr in a loop for processing row-wise or indl. values. Please see the edit above.

Siong Thye Goh · Accepted Answer · 2019-02-20 03:08:21Z

1

We can do a nested list comprehension as follows:

t = int(input("Input number of tests: ")) 
n = int(input("Input number of rows: "))#.strip().split()) 

total = [[sum([int(i) for i in input("Input score: ").split()]) for j in range(n)] for t_index in range(t)]

print(total)

Example of an input-output pair:

Input number of tests: 2
Input number of rows: 3
Input score: 1 2 3
Input score: 2 3 4
Input score: 3 4 5
Input score: 4 5 6
Input score: 5 6 7
Input score: 6 7 8
[[6, 9, 12], [15, 18, 21]]

edited Feb 20, 2019 at 3:08

answered Feb 20, 2019 at 2:59

Siong Thye Goh

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2 Comments

jiten Over a year ago

I changed to : total = [[sum([int(i) for i in input("Input score: ").split()[:l]]) for j in range(n)] for t_index in range(t)]

jiten Over a year ago

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