ruby中set方法 和範圍

 1 soyo@soyo-ThinkPad-X1:~$ irb
 2 2.4.1 :001 > require 'set'
 3  => true 
 4 2.4.1 :002 > Set.new [1,2]
 5  => #<Set: {1, 2}> 
 6 2.4.1 :003 > s =_
 7  => #<Set: {1, 2}> 
 8 2.4.1 :004 > s.add('foo')
 9  => #<Set: {1, 2, "foo"}> 
10 2.4.1 :005 > b =Set.new[2,3,4]
11 NoMethodError: undefined method `[]' for #<Set: {}>
12     from (irb):5
13     from /home/soyo/.rvm/rubies/ruby-2.4.1/bin/irb:11:in `<main>'
14 2.4.1 :006 > b  = Set.new [2,3,4]
15  => #<Set: {2, 3, 4}> 
16 2.4.1 :007 > s & b
17  => #<Set: {2}> 
18 2.4.1 :008 > s |b
19  => #<Set: {1, 2, "foo", 3, 4}> 
20 2.4.1 :009 > s <=b 
21  => false 
22 2.4.1 :010 > b <= s
23  => false 
24 2.4.1 :011 > c = Set.new [2,3]
25  => #<Set: {2, 3}> 
26 2.4.1 :012 > c <= b
27  => true 

實際運用中，set的做用：
兩個集合的交集，並集，子集

 

 

範圍

區間兩大做用：取值 ，判斷是否在區間

soyo@soyo-ThinkPad-X1:~$ irb
2.4.1 :001 > r = 1..2
 => 1..2 
2.4.1 :002 > r.include?(2)
 => true 
2.4.1 :003 > a  = [1,2,3,4]
 => [1, 2, 3, 4] 
2.4.1 :004 > a [1..2]
 => [2, 3] 
2.4.1 :005 >