Convert Any Iterable to Array in Python

Question

This just has to be a dupe, but I just didn't find any existing instance of this question...

What is the easiest way to convert any iterable to an array in Python (ideally, without importing anything)?

Note: Ideally, if the input is an array then it shouldn't duplicate it (but this isn't required).

@bradley Oh shoot, don't tell me Python doesn't have arrays!?! I thought `()` were lists and `[]` were arrays... — user541686, Jun 22 '11 at 22:48
Python does have arrays (see my answer), but they are not the same as lists. () are used for tuples. — jena, Jun 22 '11 at 22:51
@jena, @bradley: Ah thanks. If you happen to know Scheme -- so Python's tuples are the same thing as Scheme's vectors? — user541686, Jun 22 '11 at 22:56
I have never used Scheme, but if I'm not mistaken, Scheme's vectors are mutable, aren't they? Tuples in Python are immutable, so there's a difference. — jena, Jun 22 '11 at 23:00
Possible duplicate of [Fastest way to convert an iterator to a list](http://stackoverflow.com/questions/3790848/fastest-way-to-convert-an-iterator-to-a-list) — Ciro Santilli OurBigBook.com, Nov 26 '15 at 16:43

score 19 · Accepted Answer · answered Jun 22 '11 at 22:43

It depends on what you mean by array. If you really mean array and not list or the like, then you should be aware that arrays are containers of elements of the same (basic) type (see http://docs.python.org/library/array.html), i.e. not all iterables can be converted into an array. If you mean list, try the following:

l = list(iterable)

score 4 · Answer 2 · answered Jun 22 '11 at 22:40

4

If by "array" you mean a list, how about:

list(foo)

answered Jun 22 '11 at 22:40

Matti Virkkunen

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score 2 · Answer 3 · answered Jun 22 '11 at 22:39

2

What about [e for e in iterable]?

And, to satisfy the extra requirement:

iterable if isinstance(iterable,list) else [e for e in iterable]

answered Jun 22 '11 at 22:39

Alexander Gessler

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3

`[e for e in iterable]` is better written as `list(iterable)`. – Thomas Wouters Jun 22 '11 at 23:00

score 2 · Answer 4 · answered Jun 22 '11 at 22:41

The list function takes an iterable as an argument and returns a list. Here's an example:

>>> rng = xrange(10)
>>> rng
xrange(10)
>>> list(rng)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

This won't create a list of lists, either:

>>> list(list(rng))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

score 0 · Answer 5 · answered Jun 22 '11 at 22:44

0

Basically, arrays and lists are more or less the same thing in python. So a list comprehension will do the job:

  ary = [ i for i in yourthing ]

answered Jun 22 '11 at 22:44

Charlie Martin

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Convert Any Iterable to Array in Python

5 Answers5