interval_set

IntervalSet

IntervalSet implements a set of sorted non-overlapping ranges. A range's start is always interpreted as inclusive while the end is exclusive.

Installation

Add this line to your application's Gemfile:

gem 'interval_set'

And then execute:

$ bundle

Or install it yourself as:

$ gem install interval_set

Documentation

http://www.rubydoc.info/gems/interval_set

Usage

Create a interval set:

IntervalSet.new             # -> []
IntervalSet[]               # -> []
IntervalSet[0...1]          # -> [0...1]
IntervalSet[0...1, 2...3]   # -> [0...1, 2...3]
IntervalSet[0...1, 1...2]   # -> [0...2]

array = [0...1, 2...3]
IntervalSet[*array]         # -> [0...1, 2...3]

Add a range:

IntervalSet.new << (0...1)  # -> [0...1]
IntervalSet.new.add(0...1)  # -> [0...1]

i = IntervalSet.new         # -> []
i << (0...1)                # -> [0...1]
i << (2...3)                # -> [0...1, 2...3]
i << (1...2)                # -> [0...3]
i << (-1...4)               # -> [-1...4]

Remove a range:

i = IntervalSet[0...10]     # -> [0...10]
i >> (2...8)                # -> [0...2, 8...10]
i.remove(0...2)             # -> [8...10]

Get bounds:

i = IntervalSet[0...1, 2...3] # -> [0...1, 2...3]
i.min                       # -> 0
i.max                       # -> 3
i.bounds                    # -> 0...3

Check empty:

IntervalSet[].empty?        # -> true

i = IntervalSet[0...1]      # -> [0...1]
i.empty?                    # -> false
i >> (0...1)                # -> []
i.empty?                    # -> true

Count ranges:

i = IntervalSet[]           # -> []
i.count                     # -> 0
i << (0...1)                # -> [0...1]
i.count                     # -> 1
i << (2...3)                # -> [0...1, 2...3]
i.count                     # -> 2
i << (1...2)                # -> [0...3]
i.count                     # -> 1

Check inclusion:

i = IntervalSet[0...1]      # -> [0...1]

i.include?(0)               # -> true
i.include?(0.5)             # -> true
i.include?(1)               # -> false ; a range's end is exclusive

Check intersection:

i = IntervalSet[0...1]      # -> [0...1]

# Ranges only need a single common element with the interval set
i.intersect?(0...1)         # -> true
i.intersect?(0...2)         # -> true
i.intersect?(1...2)         # -> false ; the start of a range is inclusive but the end exclusive

# The same applies for interval sets
i.intersect?(IntervalSet[0...1])        # -> true
i.intersect?(IntervalSet[0...1, 2...3]) # -> true
i.intersect?(IntervalSet[2...3])        # -> false

Calculate union:

IntervalSet[0...1, 2...3] | IntervalSet[1...2, 4...5] # -> [0...3, 4...5]

Calculate intersection:

IntervalSet[0...2, 3...5] & IntervalSet[1...4, 5...6] # -> [1...2, 3...4]

Calculate difference:

IntervalSet[0...2, 3...5] - IntervalSet[1...4, 5...6] # -> [0...1, 4...5]

Calculate exclusive set:

IntervalSet[0...1] ^ IntervalSet[1...2] # -> [0...2]
IntervalSet[0...2, 4...6] ^ IntervalSet[1...5, 7...8] # -> [0...1, 2...4, 5...6, 7...8]
IntervalSet[0...1] ^ IntervalSet[0...1] # -> []

Compare sets:

# A > B is true iff A is a proper superset of B
IntervalSet[0...1] > IntervalSet[0...1]          # -> false 
IntervalSet[0...2] > IntervalSet[0...1]          # -> true 
IntervalSet[0...1] > IntervalSet[1...3]          # -> false

# A >= B is true iff A is equal to B or a proper superset
IntervalSet[0...1] >= IntervalSet[0...1]         # -> true 
IntervalSet[0...2] >= IntervalSet[0...1]         # -> true 
IntervalSet[0...1] >= IntervalSet[0...1, 2...3]  # -> false
IntervalSet[0...3] >= IntervalSet[0...1, 2...3]  # -> true

# A < B is true iff A is a proper subset of B 
# Iff A < B then A > B
IntervalSet[0...1] < IntervalSet[0...2]          # -> true 
IntervalSet[1...3] < IntervalSet[0...2]          # -> false 
IntervalSet[1...3] < IntervalSet[0...2]          # -> false

# A <= B is true iff A is equal to B or a proper subset
# Iff A <= B then A >= B
IntervalSet[0...1] <= IntervalSet[0...1]         # -> true
IntervalSet[0...1] <= IntervalSet[0...2]         # -> true 
IntervalSet[0...1, 2...3] <= IntervalSet[0...1]  # -> false 
IntervalSet[0...1, 2...3] <= IntervalSet[0...3]  # -> true 

# A == B
IntervalSet[0...1] == IntervalSet[0...1]  # -> true
IntervalSet[0...1] == IntervalSet[1...2]  # -> false

Use in case statements:

case 2.5
  when IntervalSet[0...2] then 'between 0 and 2'
  when IntervalSet[2...3] then 'between 2 and 3'
end
# -> "between 2 and 3"

Shift by a given amount:

IntervalSet[0...1].shift(1)     # -> [1...2] 

Note that shift(0) will not be optimized since IntervalSet does not assume numbers as element type.

Buffer left and right:

IntervalSet[1...2].buffer(1, 2) # -> [0...4]

# Negative values will shrink the ranges:
IntervalSet[0...4].buffer(-1, -2)     # -> [1...2]
IntervalSet[1...2].buffer(-0.5, -0.5) # -> []

Convolve sets: A ∗ B = { a + b | a ∈ A ∧ b ∈ B }

# Convolve with a range (effectively buffers the set)
IntervalSet[0...4] * (-1...2) # -> [-1...6] 

# Convolving with empty or reversed ranges result in an empty set.
IntervalSet[0...4] * (0...0)   # -> []
IntervalSet[0...4] * (1...0)   # -> []

# Convolve with a interval set
IntervalSet[0...1, 10...12] * IntervalSet[-2...1, 1...2]  # -> [-2...3, 8...14] 

Copy another interval set:

a = IntervalSet[0...1]      # -> [0...1] 
b = IntervalSet[2...3]      # -> [2...3] 

a.copy(b)

a                           # -> [2...3] 
b                           # -> [2...3] 

Clone another interval set:

a = IntervalSet[0...1]      # -> [0...1] 
b = a.clone                 # -> [0...1] 
b << (2...3)
b                           # -> [0...1, 2...3] 

Use other types:

a = Date.parse('2000-01-01') 
b = Date.parse('2000-01-02')
c = Date.parse('2000-01-03') 
 
i = IntervalSet[a...b]      # -> [2000-01-01...2000-01-02]

i << (b...c)                # -> [2000-01-01...2000-01-03] 
i.shift!(1)                 # -> [2000-01-02...2000-01-04]

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the specs. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/rjasper/ruby-interval_set. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the IntervalSet project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.