5 Best Ways to Merge Two Strings in Alternating Fashion in Python

💡 Problem Formulation: Imagine we have two strings, such as “abc” and “12345”. We want to combine these two into a single string where characters from each are alternated such as “a1b2c345”. If one string is longer than the other, the remaining characters are simply appended. This article will explore various methods for achieving this in Python.

Method 1: Loop with Manual Indexing

This approach relies on manually tracking indexes as we iterate through the characters of the two input strings. We create a result string by appending alternating characters from each string by increasing the index after each addition. This method is straightforward and easy to understand, but can be a little verbose.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

This solution uses zip() to combine equal-length padded versions of both strings. The list comprehension then concatenates the pairs, effectively interleaving the strings. Since spaces are added to match the lengths, the output remains correctly alternated, and join() takes care of empty spaces.

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

The generator expression generates a sequence of merged substrings of length 1 from either string. We use slicing to prevent index errors and join() to create the final merged string. This method handles strings of unequal lengths gracefully and is both elegant and memory-efficient.

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

The code alternates characters from both strings using chain.from_iterable() and zip(). If one string is longer than the other, we concatenate the remaining elements to the result. This approach is efficient but requires a conditional to handle excess characters.

Method 4: Using a Generator Expression

A generator expression with a custom function can also perform this task. It is an inline method of merging two strings and can be more memory-efficient as it generates values on the fly instead of creating intermediary lists or tuples.

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

We use zip_longest() to combine the two strings. The list comprehension flattens the resulting tuples, and uses join() to create a string from the alternating characters. The fillvalue='' ensures there are no gaps when one string is longer than the other.

Method 3: Using zip and chain from itertools

Combining zip() with chain() from the itertools module gives us another way to alternate between characters of two strings. The zip() function forms pairs up to the shortest input sequence, and chain() is used to append any remaining elements from the longer iterable.

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

The code defines a function merge_strings_alternately() that takes two strings as arguments. We initialize two counters, i and j, to track positions in each string. Using a while loop, we iterate through both strings and append characters alternatively to result until we reach the end of the longer string.

Method 2: Using zip_longest from itertools

The zip_longest() function from the itertools module lets us combine two iterables (strings, in this case) by yielding pairs of elements. If one iterable is shorter, it fills the missing values with a specified fillvalue (None by default). This function provides an elegant and concise way to merge strings.

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.

def merge_strings_alternately(str1, str2):
    result = ""
    i, j = 0, 0
    while i < len(str1) or j < len(str2):
        if i < len(str1):
            result += str1[i]
            i += 1
        if j < len(str2):
            result += str2[j]
            j += 1
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 2: Using zip_longest from itertools

Here’s an example:

from itertools import zip_longest

def merge_strings_alternately(str1, str2):
    result = ''.join([c for t in zip_longest(str1, str2, fillvalue='') for c in t])
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 3: Using zip and chain from itertools

Here’s an example:

from itertools import chain, zip

def merge_strings_alternately(str1, str2):
    result = ''.join(chain.from_iterable(zip(str1, str2)))
    result += str1[len(str2):] if len(str1) > len(str2) else str2[len(str1):]
    return result

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Method 4: Using a Generator Expression

Here’s an example:

def merge_strings_alternately(str1, str2):
    merged_gen = (str1[i:i+1] + str2[i:i+1] for i in range(max(len(str1), len(str2))))
    return ''.join(merged_gen)

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Bonus One-Liner Method 5: Conditional List Comprehension

The previous generator expression can be simplified into a one-liner using conditional list comprehension. While compact, readability may be sacrificed.

Here’s an example:

def merge_strings_alternately(str1, str2):
    return ''.join(s1 + s2 for s1, s2 in zip(str1 + ' '*len(str2), str2+' '*len(str1)))

print(merge_strings_alternately("apple", "123"))

Output:

a1p2p3le

Summary/Discussion

Method 1: Manual Indexing. Straightforward with explicit logic. Verbose, not the most Pythonic.
Method 2: zip_longest from itertools. Elegant and concise. Relies on external module.
Method 3: zip and chain from itertools. Efficient for handling excess elements. Requires extra handling for different length strings.
Method 4: Generator Expression. Memory-efficient and inline approach. Might be less readable to new Python users.
Method 5: One-Liner Conditional List Comprehension. Compact but potentially sacrifices readability. Creative use of Python’s capabilities.