['ruby', 'rails'].map {|str| str.upcase}
["RUBY", "RAILS"]
p [true, true, true].all?
p [true, true, false].all?
p [false, false, false].none?
p [true, true, false].any?
p [false, false, false].any?
p [true, false, false].one?
true false true true false true
true
0.zero?
true
1.one?
NoMethodError: undefined method `one?' for 1:Integer (pry):13:in `<main>' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:355:in `evaluate_ruby' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:323:in `handle_line' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:243:in `block (2 levels) in eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `catch' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:242:in `block in eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `catch' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/pry-0.10.4/lib/pry/pry_instance.rb:241:in `eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:65:in `eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/backend.rb:12:in `eval' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:87:in `execute_request' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:47:in `dispatch' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/kernel.rb:37:in `run' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:70:in `run_kernel' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/lib/iruby/command.rb:34:in `run' /Users/ariga/.rbenv/versions/2.4.0-preview2/lib/ruby/gems/2.4.0/gems/iruby-0.2.9/bin/iruby:5:in `<top (required)>' /Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `load' /Users/ariga/.rbenv/versions/2.4.0-preview2/bin/iruby:22:in `<main>'
p [4, 4, 2, 3].all? {|v| v.is_a?(Integer)}
p [4, 4, 'two'].all? {|v| v.is_a?(Integer)}
true false
false
[4, 4, 2, 3].map {|v| v.is_a?(Integer)}.all?
true
p [4, 'two', 3].map {|v| v.is_a?(Integer)}.all?
p [4, 'two', 3].all? {|v| v.is_a?(Integer)}
false false
false
p %w(Alice Bob Charlie).grep(/a/i)
['a', 'b', 3, 4].grep(String)
["Alice", "Charlie"]
["a", "b"]
String === 'a'
true
'a' === String
false
p String.===('a')
p 'a'.===(String)
true false
false
p 'a' === 'a'
'a'.methods.grep(:===)
true
[:===]
/a/i === 'Charlie'
true
array = [4, 4, 2, 3]
array.detect {|v| v.even? }
4
array.find {|v| v.odd? }
3
p array.select{|v| v.even?}
p array.reject{|v| v.even?}
[4, 4, 2] [3]
[3]
array = [1, 2, 3, 4, 5]
p array.take(3)
array.drop(3)
[1, 2, 3]
[4, 5]
array[0...3]
[1, 2, 3]
array[3..-1]
[4, 5]
p array.take_while {|n| n < 3}
array.drop_while {|n| n < 3}
[1, 2]
[3, 4, 5]
次回は 5-5-1 の「■畳み込み演算」から