5 Best Ways to Convert a List of Ints to a List of Strings in Python

Python developers often face the need to convert data from one type to another. In this article, we specifically tackle the challenge of converting a list of integers into a list of strings. For example, converting the list [1, 2, 3] to ["1", "2", "3"]. This operation is common when preparing data for serialization, output formatting, or other type-sensitive operations.

Method 1: Using a List Comprehension

This method leverages list comprehensions—a concise way to create lists in Python. It is a clear and Pythonic approach to converting each element in the list to a string.

Here’s an example:

int_list = [1, 2, 3]
str_list = [str(num) for num in int_list]

Output:

The code snippet above iterates over each integer in the list and applies the str() function, which converts the integer to a string, and then constructs a new list with these string representations.

Method 2: Using the map() Function

The map() function is a built-in Python method that applies a specified function to each item of an iterable (such as a list) and returns a list of results in Python 2.x, or a map object in Python 3.x, which can be converted into a list.

Here’s an example:

int_list = [1, 2, 3]
str_list = list(map(str, int_list))

Output:

In this example, map() applies the str() function to each element in the input list, creating a map object. Wrapping the map object with list() converts it into a list of strings.

Method 3: Using a For Loop

A for loop is a straightforward approach where each element in the integer list is converted to a string in an iterative process.

Here’s an example:

int_list = [1, 2, 3]
str_list = []
for num in int_list:
    str_list.append(str(num))

Output:

The code follows a simple loop that goes through each number in the input list, converts it to a string, and then appends it to the resultant string list.

Method 4: Using String Formatting

This method uses the string formatting operation to convert integers into strings in a formatted manner, allowing for additional flexibility, such as zero-padding or other numerical formats.

Here’s an example:

int_list = [1, 2, 3]
str_list = ["{:d}".format(i) for i in int_list]

Output:

The format specifier "{:d}" indicates that the format should treat the input as integers and convert them to strings accordingly within the list comprehension.

Bonus One-Liner Method 5: Using __str__ with map()

This one-liner is a variant of Method 2, using the special method __str__ directly instead of the str() function.

Here’s an example:

int_list = [1, 2, 3]
str_list = list(map(int.__str__, int_list))

Output:

This snippet is similar to Method 2 but calls the special method __str__ on the integer type. This way, the conversion still happens within the map function, resulting in a list of strings.

Summary/Discussion

• Method 1: List Comprehension. Effortlessly converts integers to strings within a single line. Highly readable but limited to simple conversions.
• Method 2: map() Function. Streamlines the conversion process, may be more memory-efficient in Python 3 due to lazy evaluation. Requires an extra step to convert the map object to a list in Python 3.x.
• Method 3: For Loop. Most explicit and perhaps easiest to understand for beginners. Can be less concise than other methods.
• Method 4: String Formatting. Offers customizable string representation, but potentially overkill for straightforward conversions.
• Bonus Method 5: __str__ with map(). Quick and less common, might be confusing to some as it directly uses a special method usually invoked by built-in functions.