Introducing the Range

The core of Ranger’s functionality is the Ranger.src.Range.Range.Range class. This class represent a contiguous segment of a comparable object such as an int, float, character, or date. Ranges can be open or closed on either side, meaning they can include or exclude their boundary values. Ranges can also be unbounded on either side, allowing them to stretch across the entire domain of an object.

Creating a Range

Ranges are creating using one of the static methods in the Range class. These explicitly specify the nature of the Range’s bounds (i.e. open v. closed, bounded v. unbounded)

>>> from Ranger import Range
>>> import datetime
>>> Range.closed(1,5)
[1, 5]
>>> Range.openClosed(1,5)
(1, 5]
>>> Range.closedOpen(1,5)
[1, 5)
>>> Range.open(1,5)
(1, 5)
>>> Range.greaterThan(1)
(1 , )
>>> Range.atLeast(1)
[1 , )
>>> Range.lessThan(5)
( , 5)
>>> Range.atMost(5)
( , 5]
>>> Range.closed(0.5, 0.51)
[0.5, 0.51]
>>> Range.closed('a','d')
[a, d]
>>> Range.closed(datetime.date(1985,12,21), datetime.date(1986,11,3))
[1985-12-21 , 1986-11-03]

Note that the endpoints of the Range need to be in the same class (or one needs to be in a subclass of another). For instance, observe the following error.

>>> Range.closed(1, 3.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/Ranger/src/Range/Range.py", line 364, in closed
    Range._validate_cutpoints(lower, upper)
  File "/usr/local/lib/python2.7/site-packages/Ranger/src/Range/Range.py", line 331, in _validate_cutpoints
    raise ValueError("Cutpoints are not compatible")
ValueError: Cutpoints are not compatible

Using Range objects

Range objects have a number of methods that can be used to test for membership or perform set algebraic operations. This is shown using date as an example below, but it would apply equally to any other domain.

>>> dateRange = Range.closed(datetime.date(1985,12,21), datetime.date(1986,11,3))
>>> dateRange
[1985-12-21 , 1986-11-03]
>>> dateRange.contains(datetime.date(1986,1,1))
True
>>> dateRange.contains(datetime.date(1985,1,1))
False
>>> dateRange.containsAll((datetime.date(1986,1,1), datetime.date(1986,3,17)))
True
>>> dateRange.containsAll((datetime.date(1986,1,1), datetime.date(1987,3,17)))
False
>>> smallRange = Range.closed(datetime.date(1985,12,25),datetime.date(1986,1,1))
>>> dateRange.encloses(smallRange)
True
>>> smallRange2 = Range.closed(datetime.date(1985,12,20),datetime.date(1986,1,1))
>>> dateRange.encloses(smallRange2)
False
>>> dateRange.intersection(smallRange2)
[1985-12-21 , 1986-01-01]
>>> dateRange.span(smallRange2)
[1985-12-20 , 1986-11-03]