Getting a map() to return a list in Python 3.x


Question

I'm trying to map a list into hex, and then use the list elsewhere. In python 2.6, this was easy:

A: Python 2.6:

>>> map(chr, [66, 53, 0, 94])
['B', '5', '\x00', '^']

However, in Python 3.1, the above returns a map object.

B: Python 3.1:

>>> map(chr, [66, 53, 0, 94])
<map object at 0x00AF5570>

How do I retrieve the mapped list (as in A above) on Python 3.x?

Alternatively, is there a better way of doing this? My initial list object has around 45 items and id like to convert them to hex.

1
458
10/13/2018 8:37:00 PM

Accepted Answer

Do this:

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

In Python 3+, many processes that iterate over iterables return iterators themselves. In most cases, this ends up saving memory, and should make things go faster.

If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:

# Prints "ABCD"
for ch in map(chr,[65,66,67,68]):
    print(ch)
690
8/20/2009 12:42:10 AM

Why aren't you doing this:

[chr(x) for x in [66,53,0,94]]

It's called a list comprehension. You can find plenty of information on Google, but here's the link to the Python (2.6) documentation on list comprehensions. You might be more interested in the Python 3 documenation, though.


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