Ruby: Intersection Between Two Ranges

Ruby: intersection between two ranges

require 'date'

class Range
  def intersection(other)
    return nil if (self.max < other.begin or other.max < self.begin) 
    [self.begin, other.begin].max..[self.max, other.max].min
  end
  alias_method :&, :intersection
end

p (Date.new(2011,1,1)..Date.new(2011,1,15)) & (Date.new(2011,1,10)..Date.new(2011,2,15))
#<Date: 2011-01-10 ((2455572j,0s,0n),+0s,2299161j)>..#<Date: 2011-01-15 ((2455577j,0s,0n),+0s,2299161j)>

How can I check if 2 ranges intersect in any way in ruby?

You can check if one range includes begin or end of another one:

r1 = (1..5)
r2 = (4..8)

r1.include?(r2.begin) || r1.include?(r2.end) || r2.include?(r1.begin) || r2.include?(r1.end)

In your case:

r1 = (sprite1[1]..sprite1[1] + sprite1[0].width)
r2 = (sprite2[1]..sprite2[1] + sprite2[0].width)
r1.include?(sprite2[1]) || r1.include?(sprite2[1] + sprite2[0].width) || 
  r2.include(sprite1[1]) || r2.include(sprite1[1] + sprite1[0].width)

assuming that the ranges are not endless.

Check if two ranges overlap in ruby

Two ranges overlap for a given range A when:

1. range B starts within range A,
2. range B ends within range A or
3. range B starts before range A and ends after range A

Examples:

Range A    |-----|
             |-----|  Case 1
         |-----|      Case 2
             |-|      Case 1 + 2
         |---------|  Case 3

Looking closer the rule is: Two ranges overlap when Range B starts before the range A ends and range B ends after the range A starts.

def ranges_overlap?(range_a, range_b)
  range_b.begin <= range_a.end && range_a.begin <= range_b.end 
end 

How to combine overlapping time ranges (time ranges union)

Given a function that returns truthy if two ranges overlap:

def ranges_overlap?(a, b)
  a.include?(b.begin) || b.include?(a.begin)
end

(this function courtesy of sepp2k and steenslag)

and a function that merges two overlapping ranges:

def merge_ranges(a, b)
  [a.begin, b.begin].min..[a.end, b.end].max
end

then this function, given an array of ranges, returns a new array with any overlapping ranges merged:

def merge_overlapping_ranges(overlapping_ranges)
  overlapping_ranges.sort_by(&:begin).inject([]) do |ranges, range|
    if !ranges.empty? && ranges_overlap?(ranges.last, range)
      ranges[0...-1] + [merge_ranges(ranges.last, range)]
    else
      ranges + [range]
    end
  end
end

How can I calculate the intersection of two ordinary intervals in Ruby?

This should do it.

Code

def length(a,b,p)
  [[a.last,b.last].min - [a.first,b.first].max,0].max.round(p)
end

Examples

Dynamic intersection in Ruby Arrays

arr.reduce &:&
#⇒ [
#  [0] 2,
#  [1] 4
# ]

Return object after performing intersection of two arrays based on attribute

you can:

1 :

override the eql?(other) method then the array intersection will work

class Link < ApplicationRecord
  def eql?(other)
    self.class == other.class && self.id == other&.id # classes comparing class is a guard here
  end
  
  # you should always update the hash if you are overriding the eql?() https://stackoverflow.com/a/54961965/5872935
  def hash
    self.id.hash
  end 
end

2:

use array.select:

array_links.flat_map {|i| selected_links.select {|k|  k.user_id == i.user_id }}

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