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Python – Integers String to Integer List

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Given an Integers String, composed of negative and positive numbers, convert to integer list.

Input : test_str = ‘4 5 -3 2 -100 -2’ 

Output : [4, 5, -3, 2, -100, -2] 

Explanation : Negative and positive string numbers converted to integers list. 

Input : test_str = ‘-4 -5 -3 2 -100 -2’ 

Output : [-4, -5, -3, 2, -100, -2] 

Explanation : Negative and positive string numbers converted to integers list.

Method #1 : Using list comprehension + int() + split()

In this, we split integers using split(), and int() is used for integral conversion. Elements inserted in List using list comprehension

Python3




# Python3 code to demonstrate working of
# Integers String to Integer List
# Using list comprehension + int() + split()
import string
 
# initializing string
test_str = '4 5 -3 2 -100 -2 -4 9'
 
# printing original string
print("The original string is : " + str(test_str))
 
# int() converts to required integers
res = [int(ele) for ele in test_str.split()]
     
# printing result
print("Converted Integers : " + str(res))


Output

The original string is : 4 5 -3 2 -100 -2 -4 9
Converted Integers : [4, 5, -3, 2, -100, -2, -4, 9]

Time Complexity: O(n)

Auxiliary Space: O(n)

Method #2 : Using map() + int()

In this, the task of extension of logic of integer conversion is done using map().

Python3




# Python3 code to demonstrate working of
# Integers String to Integer List
# Using map() + int()
import string
 
# initializing string
test_str = '4 5 -3 2 -100 -2 -4 9'
 
# printing original string
print("The original string is : " + str(test_str))
 
# int() converts to required integers
# map() extends logic of int to each split
res = list(map(int, test_str.split()))
     
# printing result
print("Converted Integers : " + str(res))


Output

The original string is : 4 5 -3 2 -100 -2 -4 9
Converted Integers : [4, 5, -3, 2, -100, -2, -4, 9]

Time Complexity: O(n) -> (average of map function +split)

Auxiliary Space: O(n)

Approach#3:using loop

Algorithm

1.Split the input string using the split() function.
2.Use a loop to convert each string element into an integer and append it to a new list.

Python3




test_str = '4 5 -3 2 -100 -2'
int_list = []
for x in test_str.split():
    int_list.append(int(x))
print(int_list)


Output

[4, 5, -3, 2, -100, -2]

Time Complexity: O(n), where n is the number of elements in the input string.

Space Complexity: O(n), where n is the number of elements in the input string.



Last Updated : 22 Apr, 2023
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