Python – Insert character in each duplicate string after every K elements

When it is required to insert a character in each duplicate string after every K elements, a method is defined that uses the append method, concatenation operator and list slicing to create multiple versions of the string with the character inserted at different positions.

Example

Below is a demonstration of the same −

def insert_char_after_key_elem(my_string, my_key, my_char):
    my_result = []
    for index in range(0, len(my_string), my_key):
        my_result.append(my_string[:index] + my_char + my_string[index:])
    return my_result

my_string = 'PythonToCode'

print("The string is :")
print(my_string)

K = 2
print("The value of K is")
print(K)

add_char = ";"

print("The result is :")
result = insert_char_after_key_elem(my_string, K, add_char)
for item in result:
    print(item)

Output

The string is :
PythonToCode
The value of K is
2
The result is :
;PythonToCode
Py;thonToCode
Pyth;onToCode
Python;ToCode
PythonTo;Code
PythonToCo;de

How It Works

The function works by creating multiple copies of the original string, each with the specified character inserted at different positions. The positions are determined by multiples of K (0, K, 2K, 3K, etc.). For each position, it uses string slicing to split the original string and insert the character at that position.

Alternative Implementation

Here's a more readable version that prints each result separately −

def insert_char_variations(text, step, char):
    variations = []
    for i in range(0, len(text) + 1, step):
        new_string = text[:i] + char + text[i:]
        variations.append(new_string)
    return variations

text = "Hello"
variations = insert_char_variations(text, 2, "*")

print(f"Original string: {text}")
print("Variations with '*' inserted every 2 positions:")
for i, variation in enumerate(variations):
    print(f"Position {i*2}: {variation}")

Original string: Hello
Variations with '*' inserted every 2 positions:
Position 0: *Hello
Position 2: He*llo
Position 4: Hell*o

Explanation

• A method named insert_char_after_key_elem is defined that takes a string, a key (step size) and a character as parameters.

• An empty list is defined to store the result variations.

• The function iterates through positions at intervals of K (0, K, 2K, etc.) using range(0, len(my_string), my_key).

• List slicing and concatenation operator + are used to insert the character at each position and append the result to the list.

• The method returns the list of string variations.

• Outside the method, a string is defined and displayed on the console.

• The K value and the character to insert are defined.

• The method is called with the required parameters and results are displayed.

Conclusion

This technique creates multiple string variations by inserting a character at regular intervals. It's useful for generating test data or creating formatted strings with separators at specific positions.