Convert a Map object to a List in Python

# Convert a Map object to a List in Python

Use the list() class to convert a map object to a list.

The list class takes an iterable (such as a map object) as an argument and returns a list object.

Copied!
my_list = ['1.1', '2.2', '3.3']

new_list = list(map(float, my_list))
print(new_list)  # 👉️ [1.1, 2.2, 3.3]

print(type(new_list))  # 👉️ <class 'list'>

We passed a map object to the list() class to convert it to a list.

The list class takes an iterable and returns a list object.

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

# Iterating over a Map object

If you only need to iterate over the map object, use a basic for loop.

Copied!
my_list = ['1.1', '2.2', '3.3']

map_obj = map(float, my_list)

for item in map_obj:
    # 1.1
    # 2.2
    # 3.3
    print(item)

The item variable gets set to the current map item on each iteration.

# Convert a Map object to a List using iterable unpacking

You can also use the * iterable unpacking operator to convert a map object to a list.

Copied!
my_list = ['1.1', '2.2', '3.3']

new_list = [*map(float, my_list)]

print(new_list)  # 👉️ [1.1, 2.2, 3.3]

print(type(new_list))  # 👉️ <class 'list'>

The * iterable unpacking operator enables us to unpack an iterable in function calls, in comprehensions and in generator expressions.

Copied!
result = [*(1, 2), *(3, 4), *(5, 6)]

print(result) # 👉️ [1, 2, 3, 4, 5, 6]

# Using a list comprehension instead of the map() function

An alternative approach would be to directly use a list comprehension.

Copied!
my_list = ['1.1', '2.2', '3.3']

new_list = [float(i) for i in my_list]

print(new_list)  # 👉️ [1.1, 2.2, 3.3]

In the example, we explicitly pass each list item to the float() class instead of doing it implicitly as we did with the map() function.

# Convert a Map object to a List using a for loop

You can also use a for loop to convert a map object to a list.

Copied!
my_list = ['1.1', '2.2', '3.3']

map_obj = map(float, my_list)

new_list = []

for item in map_obj:
    new_list.append(item)

print(new_list)  # 👉️ [1.1, 2.2, 3.3]

We declared a new variable and initialized it to an empty list and used a for loop to iterate over the map object.

On each iteration, we append the current item to the new list.

# Using a for loop instead of the map function

You can also use a for loop as a replacement for the map function.

Copied!
my_list = ['1.1', '2.2', '3.3']

new_list = []

for item in my_list:
    new_list.append(float(item))

print(new_list) # 👉️ [1.1, 2.2, 3.3]

We used a for loop to iterate over the list.

On each iteration, we convert the current item to a float and append the result to a new list.

As shown in the previous examples, the same can be achieved using a list comprehension or the map() function.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Get access to the Index in the map() function in Python
• Pass multiple arguments to the map() function in Python