How to Convert Python 3's `map` Object to a List?

Converting Map Objects to Lists in Python 3.x

In Python 3.x, the map() function returns an iterator by default instead of a list. This can be inconvenient if you want to use the mapped elements directly.

Problem Statement

A common task is to convert a list of integers into their hexadecimal representations. In Python 2.6, this was straightforward using the map() function, as shown below:

# Python 2.6
hex_list = map(chr, [66, 53, 0, 94])  # Return a list of hex characters

However, in Python 3.1, the above code returns a map object:

# Python 3.1
hex_map = map(chr, [66, 53, 0, 94])  # Return a map object

Solution

To retrieve the actual list of mapped elements in Python 3.x, you can use the list() function to convert the map object into a list:

hex_list = list(map(chr, [66, 53, 0, 94]))

Better Alternative

An alternative approach to mapping a list of integers to their hexadecimal representations is to use a list comprehension, as follows:

hex_list = [chr(n) for n in [66, 53, 0, 94]]

This approach eliminates the need to use the map() function and creates a list directly.

Iterating over Map Objects

Note that you can still iterate over a map object in Python 3.x without converting it to a list first:

for ch in map(chr, [65, 66, 67, 68]):
    print(ch)  # Prints "ABCD"

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