Python: Inject a number in between each pair of adjacent numbers in a list of numbers

Python Programming Puzzles: Exercise-71 with Solution

Given a list of numbers and a number to inject, write a Python program to create a list containing that number in between each pair of adjacent numbers.

Input: [12, -7, 3, -89, 14, 88, -78, -1, 2, 7]
Separator: 6
Output:
[12, 6, -7, 6, 3, 6, -89, 6, 14, 6, 88, 6, -78, 6, -1, 6, 2, 6, 7]

Input: [1, 2, 3, 4, 5, 6]
Separator: 9
Output:
[1, 9, 2, 9, 3, 9, 4, 9, 5, 9, 6]

Pictorial Presentation:

Sample Solution-1:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums, sep):
    ans = [sep] * (2 * len(nums) - 1)
    ans[::2] = nums
    return ans 
nums = [12, -7, 3, -89, 14, 88, -78, -1, 2, 7]
separator = 6
print("List of numbers:",nums)
print("Separator:",separator)
print("Inject the separator in between each pair of adjacent numbers of the said list:")
print(test(nums,separator))
nums = [1, 2, 3, 4, 5, 6]
separator = 9
print("\nList of numbers:",nums)
print("Separator:",separator)
print("Inject the separator in between each pair of adjacent numbers of the said list:")
print(test(nums,separator)) 

Sample Output:

List of numbers: [12, -7, 3, -89, 14, 88, -78, -1, 2, 7]
Separator: 6
Inject the separator in between each pair of adjacent numbers of the said list:
[12, 6, -7, 6, 3, 6, -89, 6, 14, 6, 88, 6, -78, 6, -1, 6, 2, 6, 7]

List of numbers: [1, 2, 3, 4, 5, 6]
Separator: 9
Inject the separator in between each pair of adjacent numbers of the said list:
[1, 9, 2, 9, 3, 9, 4, 9, 5, 9, 6]

Flowchart:

Sample Solution-2:

Python Code:

#License: https://bit.ly/3oLErEI

def test(nums, sep):
    result = []
    for i in range(len(nums)):
        if i == len(nums) - 1:
            result.append(nums[i])
        else:
            result.append(nums[i])
            result.append(sep)
    return result
 
nums = [12, -7, 3, -89, 14, 88, -78, -1, 2, 7]
separator = 6
print("List of numbers:",nums)
print("Separator:",separator)
print("Inject the separator in between each pair of adjacent numbers of the said list:")
print(test(nums,separator))
nums = [1, 2, 3, 4, 5, 6]
separator = 9
print("\nList of numbers:",nums)
print("Separator:",separator)
print("Inject the separator in between each pair of adjacent numbers of the said list:")
print(test(nums,separator))

Sample Output:

List of numbers: [12, -7, 3, -89, 14, 88, -78, -1, 2, 7]
Separator: 6
Inject the separator in between each pair of adjacent numbers of the said list:
[12, 6, -7, 6, 3, 6, -89, 6, 14, 6, 88, 6, -78, 6, -1, 6, 2, 6, 7]

List of numbers: [1, 2, 3, 4, 5, 6]
Separator: 9
Inject the separator in between each pair of adjacent numbers of the said list:
[1, 9, 2, 9, 3, 9, 4, 9, 5, 9, 6]

Python Code Editor :

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Find the first negative balance.
Next: Find the indices of three numbers that sum to 0 in a list.