Create List of Substrings from List of Strings in Python

In Python, when we work with lists of words or phrases, we often need to break them into smaller pieces, called substrings. A substring is a contiguous sequence of characters within a string. Creating a new list of substrings from a list of strings can be a common task in various applications. In this article, we will create a new list of substrings from a list of strings.

Create a New List of Substrings from the List of Strings

Below are some of the ways by which we can create a new list of substrings from the list of strings in Python:

Using List Comprehension

In this example, a list comprehension is employed to create a new list, `substring_list`, containing substrings extracted from each string in the `original_list`. The slicing notation `[s[1:4] for s in original_list]` extracts characters from index 1 to 3 (exclusive) from each string in the original list.

Python3

# Original list of strings
original_list = ["apple", "banana", "orange"]

# Using list comprehension to extract substrings
substring_list = [s[1:4] for s in original_list]

# Displaying the result
print(substring_list)

Output

['ppl', 'ana', 'ran']

Using map() Function

In this example, a function `extract_substring` is defined to extract a substring from a given string `s`, and the `map()` function is used to apply this function to each element in the `original_list`. The result is a new list, `substring_list`, containing the extracted substrings, which is then printed.

Python

# Original list of strings
original_list = ["apple", "banana", "orange"]

# Function to extract substring
def extract_substring(s):
    return s[1:4]

# Applying the function using map()
substring_list = list(map(extract_substring, original_list))

# Displaying the result
print(substring_list)

Output

['ppl', 'ana', 'ran']

Using Lambda Function with map() Function

In this example, a lambda function is applied using the `map()` function to extract substrings `[1:4]` from each string in the `original_list`. The result is a new list, `substring_list`, containing the extracted substrings, which is then printed.

Python

# Original list of strings
original_list = ["apple", "banana", "orange"]

# Applying a lambda function using map() for substring extraction
substring_list = list(map(lambda s: s[1:4], original_list))

# Displaying the result
print(substring_list)  # Output: ['ppl', 'ana', 'ran']

Output

['ppl', 'ana', 'ran']

Using List Comprehension with Conditional Statements

In this example, a list comprehension with a conditional statement is employed to create a new list, `substring_list`. It extracts substrings `[1:4]` from strings in the `original_list` only if the length of the string is greater than or equal to 4; otherwise, the original string is retained. The resulting list is then printed.

Python

# Original list of strings
original_list = ["apple", "banana", "orange"]

# Using list comprehension with conditional statements for substring extraction
substring_list = [s[1:4] if len(s) >= 4 else s for s in original_list]

# Displaying the result
print(substring_list)  # Output: ['ppl', 'ana', 'ran']

Output

['ppl', 'ana', 'ran']