Method # 1: Using List Comprehension
This problem can be solved by using list comprehension as a reduction in the general cycles that we would have to go through to accomplish this particular task, repeating each the line character of each list and converting to an integer.

# Python3 demo code # converting a list of strings to a list of integers # using comprehension list    # initializing list test_list = [[ `24` ], [ `45` ], [ ` 78` ], [ `40` ]]   # print original list print ( "The original list:" + str (test_list))   # using comprehension list # converting string list to list of integers res = [[ int (i) for i in sub] for i in test_list for sub in i]   # print result print ( "The list after conversion:" + str ( res))

Output:

 The original list: [[`24`], [` 45`], [`78`], [` 40`]] The list after conversion: [[2, 4], [4, 5], [7, 8], [4, 0]] 

Method # 2: Using map () + list comprehension
Problem executed in the above function can also be scaled down to include a display function that associates the conversion to integer with the function and the rest of the task is done the list comprehension function itself.

# Python3 demo code # convert a list of strings to a list integers # using a list comprehension + map ()   # initializing list test_list = [[ `24` ], [ `45` ], [ ` 78` ] , [ `40` ]]    # print original list print  ( "The original list:" + str (test_list))   # using comprehension list + map () # convert a list of strings to a list of integers res = [ list ( map ( int , list (sub [ 0 ]))) for sub in test_list if sub]    # print result print ( "The list after conversion:" + str (res))

Output:

 The original list: [[`24`], [` 45`], [`78`], [` 40`]] The list after conversion: [[2, 4], [4, 5], [7, 8], [4, 0]]