range-set

RangeSet is an integer set, implemented under the hood with ranges. The idea is that it's more efficient to store sequential data in ranges rather than as single elements. By definition, RangeSets contain no duplicates.

Installation

gem install range-set

Usage

require 'range-set'

Creating Range Sets

Use the from_array or new methods to create RangeSets:

set = RangeSet.from_array([1, 2, 3, 6, 7, 8, 11, 14, 17, 18, 19])
set.to_a  # [1..3, 6..8, 11..11, 14..14, 17..19]

The to_a method takes a boolean argument that determines whether or not to turn isolated elements into zero-length ranges or leave them as single elements:

set = RangeSet.from_array([1, 2, 3, 6, 7, 8, 11, 14, 17, 18, 19])
set.to_a(true)  # [1..3, 6..8, 11, 14, 17..19]

Union

Combining two RangeSets:

set = RangeSet.new([3..10]).union(
  RangeSet.new([9..11, 1..2, 2..3, 14..18])
)

set.to_a  # [1..11, 14..18]

Intersection

Finding the elements common to two RangeSets:

set = RangeSet.new([3..10]).intersection(RangeSet.new([1..7]))
set.to_a  # [3..7]

Subtract

Removing the elements contained in one RangeSet from another:

set = RangeSet.new([3..10]).subtract(RangeSet.new([1..5]))
set.to_a  # [6..10]

Difference

The difference here means the symmetric difference (i.e. the union without the intersection) http://en.wikipedia.org/wiki/Symmetric_difference

set = RangeSet.new([1..10]).difference(RangeSet.new([3..8]))
set.to_a  # [1..2, 9..10]

Include

set = RangeSet.new([1..5, 9..16])

set.include?(4)       # true
set.include?(6)       # false
set.include?(10..15)  # true
set.include?(4..6)    # false

Requirements

No external requirements.

Running Tests

bundle exec rake or bundle exec rspec

License

Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0