Python | Convert all strings in a list to integers



Method # 1: The Naive Method

This is the most common method that amazes any programmer when doing this kind of operation. Just looping through the entire list and converting each line of the list to int by casting.

# Python3 demo code
# convert the list of strings to int
# using the naive method

  
# initializing list

test_list = [ ` 1` , `4` , ` 3` , `6` , ` 7` ]

 
# Print original list

print ( "Original list is: " + str (test_list))

 
# using the naive method for
# perform conversion

for i in range ( 0 , len (test_list)):

  test_list [i] = int (test_list [i])

 

  
# Print modified list

print ( "Modified list is:" + str (test_list))

Output:

 Original list is: [`1`,` 4`, `3`,` 6`, `7`] Modified list is: [1, 4, 3, 6 , 7] 

Method # 2: Using List Comprehension

This is just a kind of copy of the above method, implemented using a list comprehension, a kind of shorthand which the developer is always looking for. This saves time and complexity of coding the solution.

# Python3 demo code
# list conversion lines to int
# using comprehension list

 
# initializing list

test_list = [ `1` , ` 4 ` , ` 3` , `6` , ` 7` ]

 
# Print original list

print ( "Original list is:" + str (test_list))

 
# using a list comprehension for
# perform conversion

test_list = [ int (i) for i in test_list]

  

 
# Print the modified list

print ( "Modified list is:" +   str (test_list))

Exit:

 Original list is: [`1`,` 4`, `3`,` 6`, `7`] Modified list is : [1, 4, 3, 6, 7] 

Method # 3: Using map()

This is the most elegant, pythonic and recommended method for this specific task. This function is intended solely for this kind of task and should be used to accomplish them.

Exit:

 Original list is: [`1`,` 4`, `3`,` 6`, `7`] Modified list is: [1, 4, 3, 6, 7] 

# Python3 demo code
# convert a list of strings to int
# using map ()

  
# initializing list

test_list = [ ` 1` , `4` , ` 3` , `6` , ` 7` ]

 
# Print original list

print ( "Original list is: " + str (test_list))

 
# using map () for
# perform transformation

test_list = list ( map ( int , test_list))

  

 
# Print modified list

print ( "Modified list is:" + < / code> str (test_list))