Why Is the Output of My Range Function Not a List?

Question

According to the Python documentation, when I do range(0, 10) the output of this function is a list from 0 to 9 i.e. [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]. However the Python installation on my PC is not outputting this, despite many examples of this working online.

Here is my test code...

test_range_function = range(0, 10)
print(test_range_function)
print(type(test_range_function))

The output of this I'm thinking should be the list printed, and the type function should output it as a list. Instead I'm getting the following output...

c:\Programming>python range.py
range(0, 10)
<class 'range'>

I haven't seen this in any of the examples online and would really appreciate some light being shed on this.

Answer 1

That's because range and other functional-style methods, such as map, reduce, and filter, return iterators in Python 3. In Python 2 they returned lists.

What’s New In Python 3.0:

range() now behaves like xrange() used to behave, except it works with values of arbitrary size. The latter no longer exists.

To convert an iterator to a list you can use the list function:

>>> list(range(5)) #you can use list()
[0, 1, 2, 3, 4]

Answer 2

Usually you do not need to materialize a range into an actual list but just want to iterate over it. So especially for larger ranges using an iterator saves memory.

For this reason range() in Python 3 returns an iterator instead (as xrange() did in Python 2). Use list(range(..)) if you want an actual list instead for some reason.