Python | Insert character after every character pair

Sometimes, we can have a problem in which we need to insert a specific character after pair(second) character. This kind of problem can occur while working with data, that require insertion of commas or any other special character mainly in Machine Learning domain. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using join() + list comprehension
The combination of above method can be used to perform this particular task. List comprehension along with slicing can be used to convert string to list and join function can be used to rejoin them inserting required character between them.

# Python3 code to demonstrate working of
# Insert character after every character pair
# Using join() + list comprehension

# initializing string
test_str = "GeeksforGeeks"

# printing original string
print("The original string is : " + test_str)

# Using join() + list comprehension
# Insert character after every character pair
res = ', '.join(test_str[i:i + 2] for i in range(0, len(test_str), 2))

# printing result
print("The string after inserting comma after every character pair : " + res)

Output :

The original string is : GeeksforGeeks
The string after inserting comma after every character pair : Ge, ek, sf, or, Ge, ek, s

Method #2 : Using zip() + join()
The combination of above functions can be used to perform this particular task. In this, zip function converts the characters to iterable tuples, split function is used to separate odd and even characters. Then list comprehension is responsible to convert the tuples to list of strings and at last result is joined using the join function.

# Python3 code to demonstrate working of
# Insert character after every character pair
# Using zip() + join()

# initializing string
test_str = "GeeksforGeeks"

# printing original string
print("The original string is : " + test_str)

# Using zip() + join()
# Insert character after every character pair
res = ', '.join(a + b for a, b in zip(test_str[::2], test_str[1::2]))

# printing result
print("The string after inserting comma after every character pair : " + res)

Output :

The original string is : GeeksforGeeks
The string after inserting comma after every character pair : Ge, ek, sf, or, Ge, ek