Data commit

Task/Collections/Ruby/collections-1.rb

@@ -0,0 +1,11 @@
+# creating an empty array and adding values
+a = []              #=> []
+a[0] = 1            #=> [1]
+a[3] = "abc"        #=> [1, nil, nil, "abc"]
+a << 3.14           #=> [1, nil, nil, "abc", 3.14]
+
+# creating an array with the constructor
+a = Array.new               #=> []
+a = Array.new(3)            #=> [nil, nil, nil]
+a = Array.new(3, 0)         #=> [0, 0, 0]
+a = Array.new(3){|i| i*2}   #=> [0, 2, 4]

Task/Collections/Ruby/collections-2.rb

@@ -0,0 +1,22 @@
+# creating an empty hash
+h = {}              #=> {}
+h["a"] = 1          #=> {"a"=>1}
+h["test"] = 2.4     #=> {"a"=>1, "test"=>2.4}
+h[3] = "Hello"      #=> {"a"=>1, "test"=>2.4, 3=>"Hello"}
+h = {a:1, test:2.4, World!:"Hello"}
+                    #=> {:a=>1, :test=>2.4, :World!=>"Hello"}
+
+# creating a hash with the constructor
+h = Hash.new        #=> {}   (default value : nil)
+p h[1]              #=> nil
+h = Hash.new(0)     #=> {}   (default value : 0)
+p h[1]              #=> 0
+p h                 #=> {}
+h = Hash.new{|hash, key| key.to_s}
+                    #=> {}
+p h[123]            #=> "123"
+p h                 #=> {}
+h = Hash.new{|hash, key| hash[key] = "foo#{key}"}
+                    #=> {}
+p h[1]              #=> "foo1"
+p h                 #=> {1=>"foo1"}

Task/Collections/Ruby/collections-3.rb

@@ -0,0 +1,22 @@
+# creating a struct
+
+Person = Struct.new(:name, :age, :sex)
+
+a = Person.new("Peter", 15, :Man)
+p a[0]              #=> "Peter"
+p a[:age]           #=> 15
+p a.sex             #=> :Man
+p a.to_a            #=> ["Peter", 15, :Man]
+p a.to_h            #=> {:name=>"Peter", :age=>15, :sex=>:Man}
+
+b = Person.new
+p b                 #=> #<struct Person name=nil, age=nil, sex=nil>
+b.name = "Margaret"
+b["age"] = 18
+b[-1] = :Woman
+p b.values          #=> ["Margaret", 18, :Woman]
+p b.members         #=> [:name, :age, :sex]
+p b.size            #=> 3
+
+c = Person["Daniel", 22, :Man]
+p c.to_h            #=> {:name=>"Daniel", :age=>22, :sex=>:Man}

Task/Collections/Ruby/collections-4.rb

@@ -0,0 +1,21 @@
+require 'set'
+
+# different ways of creating a set
+p s1 = Set[1, 2, 3, 4]          #=> #<Set: {1, 2, 3, 4}>
+p s2 = [8, 6, 4, 2].to_set      #=> #<Set: {8, 6, 4, 2}>
+p s3 = Set.new(1..4) {|x| x*2}  #=> #<Set: {2, 4, 6, 8}>
+
+# Union
+p s1 | s2                       #=> #<Set: {1, 2, 3, 4, 8, 6}>
+# Intersection
+p s1 & s2                       #=> #<Set: {4, 2}>
+# Difference
+p s1 - s2                       #=> #<Set: {1, 3}>
+
+p s1 ^ s2                       #=> #<Set: {8, 6, 1, 3}>
+
+p s2 == s3                      #=> true
+
+p s1.add(5)                     #=> #<Set: {1, 2, 3, 4, 5}>
+p s1 << 0                       #=> #<Set: {1, 2, 3, 4, 5, 0}>
+p s1.delete(3)                  #=> #<Set: {1, 2, 4, 5, 0}>

Task/Collections/Ruby/collections-5.rb

@@ -0,0 +1,24 @@
+require 'matrix'
+
+# creating a matrix
+p m0 = Matrix.zero(3)       #=> Matrix[[0, 0, 0], [0, 0, 0], [0, 0, 0]]
+p m1 = Matrix.identity(3)   #=> Matrix[[1, 0, 0], [0, 1, 0], [0, 0, 1]]
+p m2 = Matrix[[11, 12], [21, 22]]
+                            #=> Matrix[[11, 12], [21, 22]]
+p m3 = Matrix.build(3) {|row, col| row - col}
+                            #=> Matrix[[0, -1, -2], [1, 0, -1], [2, 1, 0]]
+
+p m2[0,0]               #=> 11
+p m1 * 5                #=> Matrix[[5, 0, 0], [0, 5, 0], [0, 0, 5]]
+p m1 + m3               #=> Matrix[[1, -1, -2], [1, 1, -1], [2, 1, 1]]
+p m1 * m3               #=> Matrix[[0, -1, -2], [1, 0, -1], [2, 1, 0]]
+
+# creating a Vector
+p v1 = Vector[1,3,5]    #=> Vector[1, 3, 5]
+p v2 = Vector[0,1,2]    #=> Vector[0, 1, 2]
+p v1[1]                 #=> 3
+p v1 * 2                #=> Vector[2, 6, 10]
+p v1 + v2               #=> Vector[1, 4, 7]
+
+p m1 * v1               #=> Vector[1, 3, 5]
+p m3 * v1               #=> Vector[-13, -4, 5]

Task/Collections/Ruby/collections-6.rb

@@ -0,0 +1,23 @@
+require 'ostruct'
+
+# creating a OpenStruct
+ab = OpenStruct.new
+p ab                #=> #<OpenStruct>
+ab.foo = 25
+p ab.foo            #=> 25
+ab[:bar] = 2
+p ab["bar"]         #=> 2
+p ab                #=> #<OpenStruct foo=25, bar=2>
+ab.delete_field("foo")
+p ab.foo            #=> nil
+p ab                #=> #<OpenStruct bar=2>
+
+p son = OpenStruct.new({ :name => "Thomas", :age => 3 })
+                    #=> #<OpenStruct name="Thomas", age=3>
+p son.name          #=> "Thomas"
+p son[:age]         #=> 3
+son.age += 1
+p son.age           #=> 4
+son.items = ["candy","toy"]
+p son.items         #=> ["candy","toy"]
+p son               #=> #<OpenStruct name="Thomas", age=4, items=["candy", "toy"]