我在
Ruby中有很多时间范围：
period = Time.parse('8:00am')..Time.parse('8:00pm')
incidents = [
Time.parse('7:00am')..Time.parse('9:00am'),Time.parse('1:00pm')..Time.parse('3:00pm'),Time.parse('1:30pm')..Time.parse('3:30pm'),Time.parse('7:00pm')..Time.parse('9:00pm'),]
我正试图在这段时间内获得一系列事件免费块.对于上面那个是：
[
Time.parse('9:00am')..Time.parse('1:00pm')
Time.parse('3:30pm')..Time.parse('7:00pm')
]
从上面可以看出事件在这段时间之外重叠或延伸.范围或类似的任何操作是否会使这种计算更简单？
解决方法
令full_range为范围,范围为范围数组,分别代表提问者所称的期间和事件.我假设所有范围中包含的元素都可以是任何对象,只要它们可以与适用的类’方法< =>进行比较.并且已包含模块
Comparable.
码
def uncovered_ranges(full_range,ranges)
ucrs = [full_range]
ranges.each do |r|
ucrs = ucrs.flat_map do |ucr|
if ucr.first >= r.last || ucr.last <= r.first
ucr
elsif r.first <= ucr.first && r.last >= ucr.last
nil
elsif r.first <= ucr.first && r.last < ucr.last
r.last..ucr.last
elsif r.first > ucr.first && r.last >= ucr.last
ucr.first..r.first
else
[ucr.first..r.first,r.last..ucr.last]
end
end.compact
end
ucrs
end
例子
full_range = 1..20
ranges = [3..4,6..8,10..12,8..14,16..17,20..20]
uncovered_ranges(full_range,ranges)
#=> [1..3,4..6,14..16,17..20]
require 'time'
full_range = Time.parse('8:00am')..Time.parse('8:00pm')
#=> 2016-12-22 08:00:00 -0800..2016-12-22 20:00:00 -0800
ranges = [
Time.parse('7:00am')..Time.parse('9:00am'),]
#=> [2016-12-22 07:00:00 -0800..2016-12-22 09:00:00 -0800,# 2016-12-22 13:00:00 -0800..2016-12-22 15:00:00 -0800,# 2016-12-22 13:30:00 -0800..2016-12-22 15:30:00 -0800,# 2016-12-22 19:00:00 -0800..2016-12-22 21:00:00 -0800]
uncovered_ranges(full_range,ranges)
#=> [2016-12-22 09:00:00 -0800..2016-12-22 13:00:00 -0800,# 2016-12-22 15:30:00 -0800..2016-12-22 19:00:00 -0800]
说明
对我来说,解释正在发生的事情的最简单和最直接的方式可能是插入一些puts语句并运行上面第一个例子的代码.
def uncovered_ranges(full_range,ranges)
ucrs = [full_range]
puts "ucrs initially=#{ucrs}"
ranges.each do |r|
puts "\ncovering range r=#{r}"
ucrs = ucrs.flat_map do |ucr|
puts " range uncovered so far ucr=#{ucr}"
if ucr.first >= r.last || ucr.last <= r.first
puts " in if #1,returning #{ucr}"
ucr
elsif r.first <= ucr.first && r.last >= ucr.last
puts " in if #2,returning nil"
nil
elsif r.first <= ucr.first && r.last < ucr.last
puts " in if #3,returning #{r.last..ucr.last}"
r.last..ucr.last
elsif r.first > ucr.first && r.last >= ucr.last
puts " in if #4,returning #{ucr.first..r.first}"
ucr.first..r.first
else
puts " in else,returning #{[ucr.first..r.first,r.last..ucr.last]}"
[ucr.first..r.first,r.last..ucr.last]
end
end.tap { |u| puts "ucrs after processing range #{r}=#{u}" }.
compact.
tap { |u| puts "ucrs after compact=#{u}" }
end
ucrs
end
uncovered_ranges 1..20,[3..4,20..20]
打印以下内容.
ucrs initially=[1..20]
covering range r=3..4 range uncovered so far ucr=1..20 in else,returning [1..3,4..20] ucrs after processing range 3..4=[1..3,4..20] ucrs after compact=[1..3,4..20]
covering range r=6..8 range uncovered so far ucr=1..3 in if #1,returning 1..3 range uncovered so far ucr=4..20 in else,returning [4..6,8..20] ucrs after processing range 6..8=[1..3,8..20] ucrs after compact=[1..3,8..20]
covering range r=10..12 range uncovered so far ucr=1..3 in if #1,returning 1..3 range uncovered so far ucr=4..6 in if #1,returning 4..6 range uncovered so far ucr=8..20 in else,returning [8..10,12..20] ucrs after processing range 10..12=[1..3,8..10,12..20] ucrs after compact=[1..3,12..20]
covering range r=8..14 range uncovered so far ucr=1..3 in if #1,returning 4..6 range uncovered so far ucr=8..10 in if #2,returning nil range uncovered so far ucr=12..20 in if #3,returning 14..20 ucrs after processing range 8..14=[1..3,nil,14..20] ucrs after compact=[1..3,14..20]
covering range r=16..17 range uncovered so far ucr=1..3 in if #1,returning 4..6 range uncovered so far ucr=14..20 in else,returning [14..16,17..20] ucrs after processing range 16..17=[1..3,17..20] ucrs after compact=[1..3,17..20]
covering range r=20..20 range uncovered so far ucr=1..3 in if #1,returning 4..6 range uncovered so far ucr=14..16 in if #1,returning 14..16 range uncovered so far ucr=17..20 in if #1,returning 17..20 ucrs after processing range 20..20=[1..3,17..20] #=> [1..3,17..20]