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Python | Converting all strings in list to integers
  • Difficulty Level : Basic
  • Last Updated : 29 Nov, 2018

Interconversion between data types is facilitated by python libraries quite easily. But the problem of converting the entire list of string to integers is quite common in development domain. Let’s discuss few ways to solve this particular problem.

Method #1 : Naive Method

This is most generic method that strikes any programmer while performing this kind of operation. Just looping over whole list and convert each of the string of list to int by type casting.




# Python3 code to demonstrate 
# converting list of strings to int
# using naive method 
  
# initializing list 
test_list = ['1', '4', '3', '6', '7']
  
# Printing original list
print ("Original list is : " + str(test_list))
  
# using naive method to
# perform conversion
for i in range(0, len(test_list)):
    test_list[i] = int(test_list[i])
      
  
# Printing 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 replica of the above method, just implemented using list comprehension, kind of shorthand that a developer looks for always. It saves time and complexity of coding a solution.




# Python3 code to demonstrate 
# converting list of strings to int
# using list comprehension
  
# initializing list 
test_list = ['1', '4', '3', '6', '7']
  
# Printing original list
print ("Original list is : " + str(test_list))
  
# using list comprehension to
# perform conversion
test_list = [int(i) for i in test_list]
      
  
# Printing 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 #3 : Using map()

This is the most elegant, pythonic and recommended method to perform this particular task. This function is exclusively made for this kind of task and should be used to perform them.




# Python3 code to demonstrate 
# converting list of strings to int
# using map()
  
# initializing list 
test_list = ['1', '4', '3', '6', '7']
  
# Printing original list
print ("Original list is : " + str(test_list))
  
# using map() to
# perform conversion
test_list = list(map(int, test_list))
      
  
# Printing 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]

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