Python range(): Represent Numerical Ranges

This repository holds the code for Real Python's Python range(): Represent Numerical Ranges tutorial.

reverse_range()

In reverse_range.py, you can find an explicit implementation of a function that can reverse a general range.

>>> from reverse_range import reverse_range

>>> reverse_range(range(1, 20, 4))
range(17, 0, -4)

>>> list(reverse_range(range(1, 20, 4)))
[17, 13, 9, 5, 1]

In practical applications, you should use reversed(range(1, 20, 4)) or range(1, 20, 4)[::-1] instead.

PiDigits

The file pi_digits.py shows the implementation of PiDigits which is an integer-like type that can be used as arguments to range():

>>> from pi_digits import PiDigits

>>> PiDigits(3)
PiDigits(num_digits=3)

>>> int(PiDigits(3))
314

>>> range(PiDigits(3))
range(0, 314)

See the tutorial for more details.

FloatRange

In float_range.py, you'll find an implementation of a custom FloatRange class that behaves similarly to the built-in range() except that its arguments can be floating point numbers:

>>> from float_range import FloatRange

>>> FloatRange(1, 10, 1.2)
FloatRange(start=1, stop=10, step=1.2)

>>> list(FloatRange(1, 10, 1.2))
[1.0, 2.2, 3.4, 4.6, 5.8, 7.0, 8.2, 9.4]

The built-in range() is implemented in C. However, you can look at the source code of FloatRange to get an idea of how range() works under the hood.

If you need to work with floating-point ranges, you can use FloatRange. However, NumPy's arange() will give you better performance, and is probably a better option overall.

Author

• Geir Arne Hjelle, E-mail: geirarne@realpython.com

License

Distributed under the MIT license. See LICENSE for more information.