Class: Hamster::Vector

Inherits:
Object
  • Object
show all
Includes:
Associable, Enumerable
Defined in:
lib/hamster/vector.rb

Overview

A Vector is an ordered, integer-indexed collection of objects. Like Ruby's Array, Vector indexing starts at zero and negative indexes count back from the end.

Vector has a similar interface to Array. The main difference is methods that would destructively update an Array (such as #insert or #delete_at) instead return new Vectors and leave the existing one unchanged.

Creating New Vectors

Hamster::Vector.new([:first, :second, :third])
Hamster::Vector[1, 2, 3, 4, 5]

Retrieving Items from Vectors

vector = Hamster::Vector[1, 2, 3, 4, 5]

vector[0]      # => 1
vector[-1]     # => 5
vector[0,3]    # => Hamster::Vector[1, 2, 3]
vector[1..-1]  # => Hamster::Vector[2, 3, 4, 5]
vector.first   # => 1
vector.last    # => 5

Creating Modified Vectors

vector.add(6)            # => Hamster::Vector[1, 2, 3, 4, 5, 6]
vector.insert(1, :a, :b) # => Hamster::Vector[1, :a, :b, 2, 3, 4, 5]
vector.delete_at(2)      # => Hamster::Vector[1, 2, 4, 5]
vector + [6, 7]          # => Hamster::Vector[1, 2, 3, 4, 5, 6, 7]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Associable

#dig, #update_in

Methods included from Enumerable

#<=>, #==, #compact, #each_index, #grep, #grep_v, #group_by, #inspect, #join, #partition, #reject, #sum, #to_set

Methods included from Enumerable

#to_list

Constructor Details

#initialize(items = [].freeze) ⇒ Vector

Returns a new instance of Vector.



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# File 'lib/hamster/vector.rb', line 85

def initialize(items=[].freeze)
  items = items.to_a
  if items.size <= 32
    items = items.dup.freeze if !items.frozen?
    @root, @size, @levels = items, items.size, 0
  else
    root, size, levels = items, items.size, 0
    while root.size > 32
      root = root.each_slice(32).to_a
      levels += 1
    end
    @root, @size, @levels = root.freeze, size, levels
  end
end

Instance Attribute Details

#size ⇒ Integer (readonly) Also known as: length

Return the number of items in this Vector

Returns:

  • (Integer) 


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# File 'lib/hamster/vector.rb', line 53

def size
  @size
end

Class Method Details

.[](*items) ⇒ Vector

Create a new Vector populated with the given items.

Returns:



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# File 'lib/hamster/vector.rb', line 59

def [](*items)
  new(items.freeze)
end

.empty ⇒ Vector

Return an empty Vector. If used on a subclass, returns an empty instance of that class.

Returns:



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# File 'lib/hamster/vector.rb', line 67

def empty
  @empty ||= self.new
end

Instance Method Details

#*(times) ⇒ Vector

Repetition. Return a new Vector built by concatenating times copies of this one together.

Examples:

Hamster::Vector["A", "B"] * 3
# => Hamster::Vector["A", "B", "A", "B", "A", "B"]

Parameters:

  • times (Integer) —

    The number of times to repeat the elements in this vector

Returns:



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# File 'lib/hamster/vector.rb', line 746

def *(times)
  return self.class.empty if times == 0
  return self if times == 1
  result = (to_a * times)
  result.is_a?(Array) ? self.class.new(result) : result
end

#+(other) ⇒ Vector Also known as: concat

Return a new Vector built by concatenating this one with other. other can be any object which is convertible to an Array using #to_a.

Examples:

Hamster::Vector["A", "B", "C"] + ["D", "E"]
# => Hamster::Vector["A", "B", "C", "D", "E"]

Parameters:

  • other (Enumerable) —

    The collection to concatenate onto this vector

Returns:



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# File 'lib/hamster/vector.rb', line 599

def +(other)
  other = other.to_a
  other = other.dup if other.frozen?
  replace_suffix(@size, other)
end

#add(item) ⇒ Vector Also known as: <<, push

Return a new Vector with item added after the last occupied position.

Examples:

Hamster::Vector[1, 2].add(99)  # => Hamster::Vector[1, 2, 99]

Parameters:

  • item (Object) —

    The object to insert at the end of the vector

Returns:



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# File 'lib/hamster/vector.rb', line 134

def add(item)
  update_root(@size, item)
end

#assoc(obj) ⇒ Object

Assumes all elements are nested, indexable collections, and searches through them, comparing obj with the first element of each nested collection. Return the first nested collection which matches, or nil if none is found. Behaviour is undefined when elements do not meet assumptions (i.e. are not indexable collections).

Examples:

v = Hamster::Vector[["A", 10], ["B", 20], ["C", 30]]
v.assoc("B")  # => ["B", 20]

Parameters:

  • obj (Object) —

    The object to search for

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 1238

def assoc(obj)
  each do |array|
    next if !array.respond_to?(:[])
    return array if obj == array[0]
  end
  nil
end

#bsearch {|element| ... } ⇒ Object

Finds a value from this Vector which meets the condition defined by the provided block, using a binary search. The vector must already be sorted with respect to the block. See Ruby's Array#bsearch for details, behaviour is equivalent.

Examples:

v = Hamster::Vector[1, 3, 5, 7, 9, 11, 13]
# Block returns true/false for exact element match:
v.bsearch { |e| e > 4 }      # => 5
# Block returns number to match an element in 4 <= e <= 7:
v.bsearch { |e| 1 - e / 4 }  # => 7

Yields:

  • Once for at most log n elements, where n is the size of the vector. The exact elements and ordering are undefined.

Yield Parameters:

  • element (Object) —

    element to be evaluated

Yield Returns:

  • (Boolean) —

    true if this element matches the criteria, false otherwise.

  • (Integer) —

    See Array#bsearch for details.

Returns:

  • (Object) —

    The matched element, or nil if none found.

Raises:

  • TypeError if the block returns a non-numeric, non-boolean, non-nil value.



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# File 'lib/hamster/vector.rb', line 1132

def bsearch
  return enum_for(:bsearch) if not block_given?
  low, high, result = 0, @size, nil
  while low < high
    mid = (low + ((high - low) >> 1))
    val = get(mid)
    v   = yield val
    if v.is_a? Numeric
      if v == 0
        return val
      elsif v > 0
        high = mid
      else
        low = mid + 1
      end
    elsif v == true
      result = val
      high = mid
    elsif !v
      low = mid + 1
    else
      raise TypeError, "wrong argument type #{v.class} (must be numeric, true, false, or nil)"
    end
  end
  result
end

#clear ⇒ Vector

Return an empty Vector instance, of the same class as this one. Useful if you have multiple subclasses of Vector and want to treat them polymorphically.

Returns:



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# File 'lib/hamster/vector.rb', line 1163

def clear
  self.class.empty
end

#combination(n) ⇒ self, Enumerator

When invoked with a block, yields all combinations of length n of items from the Vector, and then returns self. There is no guarantee about which order the combinations will be yielded.

If no block is given, an Enumerator is returned instead.

Examples:

v = Hamster::Vector[5, 6, 7, 8]
v.combination(3) { |c| puts "Combination: #{c}" }

Combination: [5, 6, 7]
Combination: [5, 6, 8]
Combination: [5, 7, 8]
Combination: [6, 7, 8]
#=> Hamster::Vector[5, 6, 7, 8]

Returns:

  • (self, Enumerator) 


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# File 'lib/hamster/vector.rb', line 825

def combination(n)
  return enum_for(:combination, n) if not block_given?
  return self if n < 0 || @size < n
  if n == 0
    yield []
  elsif n == 1
    each { |item| yield [item] }
  elsif n == @size
    yield self.to_a
  else
    combos = lambda do |result,index,remaining|
      while @size - index > remaining
        if remaining == 1
          yield result.dup << get(index)
        else
          combos[result.dup << get(index), index+1, remaining-1]
        end
        index += 1
      end
      index.upto(@size-1) { |i| result << get(i) }
      yield result
    end
    combos[[], 0, n]
  end
  self
end

#delete(obj) ⇒ Vector

Return a new Vector with all items which are equal to obj removed. #== is used for checking equality.

Examples:

Hamster::Vector["C", "B", "A", "B"].delete("B")  # => Hamster::Vector["C", "A"]

Parameters:

  • obj (Object) —

    The object to remove (every occurrence)

Returns:



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# File 'lib/hamster/vector.rb', line 476

def delete(obj)
  select { |item| item != obj }
end

#delete_at(index) ⇒ Vector

Return a new Vector with the element at index removed. If the given index does not exist, return self.

Examples:

Hamster::Vector["A", "B", "C", "D"].delete_at(2)
# => Hamster::Vector["A", "B", "D"]

Parameters:

  • index (Integer) —

    The index to remove

Returns:



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# File 'lib/hamster/vector.rb', line 372

def delete_at(index)
  return self if index >= @size || index < -@size
  index += @size if index < 0

  suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, [])
  replace_suffix(index, suffix.tap { |a| a.shift })
end

#drop(n) ⇒ Vector

Drop the first n elements and return the rest in a new Vector.

Examples:

Hamster::Vector["A", "B", "C", "D", "E", "F"].drop(2)
# => Hamster::Vector["C", "D", "E", "F"]

Parameters:

  • n (Integer) —

    The number of elements to remove

Returns:

Raises:

  • ArgumentError if n is negative.



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# File 'lib/hamster/vector.rb', line 689

def drop(n)
  return self if n == 0
  return self.class.empty if n >= @size
  raise ArgumentError, "attempt to drop negative size" if n < 0
  self.class.new(flatten_suffix(@root, @levels * BITS_PER_LEVEL, n, []))
end

#drop_while ⇒ Vector, Enumerator

Drop elements up to, but not including, the first element for which the block returns nil or false. Gather the remaining elements into a new Vector. If no block is given, an Enumerator is returned instead.

Examples:

Hamster::Vector[1, 3, 5, 7, 6, 4, 2].drop_while { |e| e < 5 }
# => Hamster::Vector[5, 7, 6, 4, 2]

Returns:



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# File 'lib/hamster/vector.rb', line 718

def drop_while
  return enum_for(:drop_while) if not block_given?
  self.class.new(super)
end

#each(&block) ⇒ self, Enumerator

Call the given block once for each item in the vector, passing each item from first to last successively to the block. If no block is given, an Enumerator is returned instead.

Examples:

Hamster::Vector["A", "B", "C"].each { |e| puts "Element: #{e}" }

Element: A
Element: B
Element: C
# => Hamster::Vector["A", "B", "C"]

Returns:

  • (self, Enumerator) 


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# File 'lib/hamster/vector.rb', line 429

def each(&block)
  return to_enum unless block_given?
  traverse_depth_first(@root, @levels, &block)
  self
end

#empty? ⇒ Boolean

Return true if this Vector contains no items.

Returns:

  • (Boolean) 


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# File 'lib/hamster/vector.rb', line 103

def empty?
  @size == 0
end

#eql?(other) ⇒ Boolean

Return true if other has the same type and contents as this Vector.

Parameters:

  • other (Object) —

    The collection to compare with

Returns:

  • (Boolean) 


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# File 'lib/hamster/vector.rb', line 1285

def eql?(other)
  return true if other.equal?(self)
  return false unless instance_of?(other.class) && @size == other.size
  @root.eql?(other.instance_variable_get(:@root))
end

#fetch(index) ⇒ Object #fetch(index) {|index| ... } ⇒ Object #fetch(index, default) ⇒ Object

Retrieve the value at index with optional default.

Overloads:

  • #fetch(index) ⇒ Object

    Retrieve the value at the given index, or raise an IndexError if not found.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D"]
v.fetch(2)       # => "C"
v.fetch(-1)      # => "D"
v.fetch(4)       # => IndexError: index 4 outside of vector bounds

    Parameters:

    • index (Integer) —

      The index to look up

    Raises:

    • (IndexError) —

      if index does not exist

  • #fetch(index) {|index| ... } ⇒ Object

    Retrieve the value at the given index, or return the result of yielding the block if not found.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D"]
v.fetch(2) { |i| i * i }   # => "C"
v.fetch(4) { |i| i * i }   # => 16

    Parameters:

    • index (Integer) —

      The index to look up

    Yields:

    • Once if the index is not found.

    Yield Parameters:

    • index (Integer) —

      The index which does not exist

    Yield Returns:

    • (Object) —

      Default value to return

  • #fetch(index, default) ⇒ Object

    Retrieve the value at the given index, or return the provided default value if not found.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D"]
v.fetch(2, "Z")  # => "C"
v.fetch(4, "Z")  # => "Z"

    Parameters:

    • index (Integer) —

      The index to look up

    • default (Object) —

      Object to return if the key is not found

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 260

def fetch(index, default = (missing_default = true))
  if index >= -@size && index < @size
    get(index)
  elsif block_given?
    yield(index)
  elsif !missing_default
    default
  else
    raise IndexError, "index #{index} outside of vector bounds"
  end
end

#fill(object) ⇒ Vector #fill(object, index) ⇒ Vector #fill(object, index, length) ⇒ Vector

Replace a range of indexes with the given object.

Overloads:

  • #fill(object) ⇒ Vector

    Return a new Vector of the same size, with every index set to object.

    Examples:

    Hamster::Vector["A", "B", "C", "D", "E", "F"].fill("Z")
# => Hamster::Vector["Z", "Z", "Z", "Z", "Z", "Z"]

    Parameters:

    • object (Object) —

      Fill value.

  • #fill(object, index) ⇒ Vector

    Return a new Vector with all indexes from index to the end of the vector set to object.

    Examples:

    Hamster::Vector["A", "B", "C", "D", "E", "F"].fill("Z", 3)
# => Hamster::Vector["A", "B", "C", "Z", "Z", "Z"]

    Parameters:

    • object (Object) —

      Fill value.

    • index (Integer) —

      Starting index. May be negative.

  • #fill(object, index, length) ⇒ Vector

    Return a new Vector with length indexes, beginning from index, set to object. Expands the Vector if length would extend beyond the current length.

    Examples:

    Hamster::Vector["A", "B", "C", "D", "E", "F"].fill("Z", 3, 2)
# => Hamster::Vector["A", "B", "C", "Z", "Z", "F"]
Hamster::Vector["A", "B"].fill("Z", 1, 5)
# => Hamster::Vector["A", "Z", "Z", "Z", "Z", "Z"]

    Parameters:

    • object (Object) —

      Fill value.

    • index (Integer) —

      Starting index. May be negative.

    • length (Integer)

Returns:

Raises:

  • (IndexError) —

    if index is out of negative range.



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# File 'lib/hamster/vector.rb', line 790

def fill(object, index = 0, length = nil)
  raise IndexError if index < -@size
  index += @size if index < 0
  length ||= @size - index # to the end of the array, if no length given

  if index < @size
    suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, [])
    suffix.fill(object, 0, length)
  elsif index == @size
    suffix = Array.new(length, object)
  else
    suffix = Array.new(index - @size, nil).concat(Array.new(length, object))
    index = @size
  end

  replace_suffix(index, suffix)
end

#first ⇒ Object

Return the first item in the Vector. If the vector is empty, return nil.

Examples:

Hamster::Vector["A", "B", "C"].first  # => "A"

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 113

def first
  get(0)
end

#flat_map ⇒ Vector

Return a new Vector with the concatenated results of running the block once for every element in this Vector.

Examples:

Hamster::Vector[1, 2, 3].flat_map { |x| [x, -x] }
# => Hamster::Vector[1, -1, 2, -2, 3, -3]

Returns:



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# File 'lib/hamster/vector.rb', line 503

def flat_map
  return enum_for(:flat_map) if not block_given?
  return self if empty?
  self.class.new(super)
end

#flatten(level = -1)) ⇒ Vector

Return a new Vector with all nested vectors and arrays recursively "flattened out". That is, their elements inserted into the new Vector in the place where the nested array/vector originally was. If an optional level argument is provided, the flattening will only be done recursively that number of times. A level of 0 means not to flatten at all, 1 means to only flatten nested arrays/vectors which are directly contained within this Vector.

Examples:

v = Hamster::Vector["A", Hamster::Vector["B", "C", Hamster::Vector["D"]]]
v.flatten(1)
# => Hamster::Vector["A", "B", "C", Hamster::Vector["D"]]
v.flatten
# => Hamster::Vector["A", "B", "C", "D"]

Parameters:

  • level (Integer) (defaults to: -1)) —

    The depth to which flattening should be applied

Returns:



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# File 'lib/hamster/vector.rb', line 578

def flatten(level = -1)
  return self if level == 0
  array = self.to_a
  if array.frozen?
    self.class.new(array.flatten(level).freeze)
  elsif array.flatten!(level) # returns nil if no changes were made
    self.class.new(array.freeze)
  else
    self
  end
end

#get(index) ⇒ Object Also known as: at

Retrieve the item at index. If there is none (either the provided index is too high or too low), return nil.

Examples:

v = Hamster::Vector["A", "B", "C", "D"]
v.get(2)   # => "C"
v.get(-1)  # => "D"
v.get(4)   # => nil

Parameters:

  • index (Integer) —

    The index to retrieve

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 213

def get(index)
  return nil if @size == 0
  index += @size if index < 0
  return nil if index >= @size || index < 0
  leaf_node_for(@root, @levels * BITS_PER_LEVEL, index)[index & INDEX_MASK]
end

#hash ⇒ Integer

See Object#hash.

Returns:

  • (Integer) 


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# File 'lib/hamster/vector.rb', line 1293

def hash
  reduce(0) { |hash, item| (hash << 5) - hash + item.hash }
end

#insert(index, *items) ⇒ Vector

Return a new Vector with the given values inserted before the element at index. If index is greater than the current length, nil values are added to pad the Vector to the required size.

Examples:

Hamster::Vector["A", "B", "C", "D"].insert(2, "X", "Y", "Z")
# => Hamster::Vector["A", "B", "X", "Y", "Z", "C", "D"]
Hamster::Vector[].insert(2, "X", "Y", "Z")
# => Hamster::Vector[nil, nil, "X", "Y", "Z"]

Parameters:

  • index (Integer) —

    The index where the new items should go

  • items (Array) —

    The items to add

Returns:

Raises:

  • (IndexError) —

    if index exceeds negative range.



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# File 'lib/hamster/vector.rb', line 346

def insert(index, *items)
  raise IndexError if index < -@size
  index += @size if index < 0

  if index < @size
    suffix = flatten_suffix(@root, @levels * BITS_PER_LEVEL, index, [])
    suffix.unshift(*items)
  elsif index == @size
    suffix = items
  else
    suffix = Array.new(index - @size, nil).concat(items)
    index = @size
  end

  replace_suffix(index, suffix)
end

#last ⇒ Object

Return the last item in the Vector. If the vector is empty, return nil.

Examples:

Hamster::Vector["A", "B", "C"].last  # => "C"

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 123

def last
  get(-1)
end

#map ⇒ Vector, Enumerator Also known as: collect

Invoke the given block once for each item in the vector, and return a new Vector containing the values returned by the block. If no block is provided, return an enumerator.

Examples:

Hamster::Vector[3, 2, 1].map { |e| e * e }  # => Hamster::Vector[9, 4, 1]

Returns:



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# File 'lib/hamster/vector.rb', line 488

def map
  return enum_for(:map) if not block_given?
  return self if empty?
  self.class.new(super)
end

#permutation(n = @size) ⇒ self, Enumerator

Yields all permutations of length n of items from the Vector, and then returns self. If no length n is specified, permutations of all elements will be yielded.

There is no guarantee about which order the permutations will be yielded in.

If no block is given, an Enumerator is returned instead.

Examples:

v = Hamster::Vector[5, 6, 7]
v.permutation(2) { |p| puts "Permutation: #{p}" }

Permutation: [5, 6]
Permutation: [5, 7]
Permutation: [6, 5]
Permutation: [6, 7]
Permutation: [7, 5]
Permutation: [7, 6]
# => Hamster::Vector[5, 6, 7]

Returns:

  • (self, Enumerator) 


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# File 'lib/hamster/vector.rb', line 928

def permutation(n = @size)
  return enum_for(:permutation, n) if not block_given?
  if n < 0 || @size < n
    # yield nothing
  elsif n == 0
    yield []
  elsif n == 1
    each { |item| yield [item] }
  else
    used, result = [], []
    perms = lambda do |index|
      0.upto(@size-1) do |i|
        if !used[i]
          result[index] = get(i)
          if index < n-1
            used[i] = true
            perms[index+1]
            used[i] = false
          else
            yield result.dup
          end
        end
      end
    end
    perms[0]
  end
  self
end

#pop ⇒ Vector

Return a new Vector with the last element removed. Return self if empty.

Examples:

Hamster::Vector["A", "B", "C"].pop  # => Hamster::Vector["A", "B"]

Returns:



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# File 'lib/hamster/vector.rb', line 387

def pop
  return self if @size == 0
  replace_suffix(@size-1, [])
end

#product(*vectors) ⇒ Vector #product ⇒ Vector

Cartesian product or multiplication.

Overloads:

  • #product(*vectors) ⇒ Vector

    Return a Vector of all combinations of elements from this Vector and each of the given vectors or arrays. The length of the returned Vector is the product of self.size and the size of each argument vector or array.

    Examples:

    v1 = Hamster::Vector[1, 2, 3]
v2 = Hamster::Vector["A", "B"]
v1.product(v2)
# => [[1, "A"], [1, "B"], [2, "A"], [2, "B"], [3, "A"], [3, "B"]]
  • #product ⇒ Vector

    Return the result of multiplying all the items in this Vector together.

    Examples:

    Hamster::Vector[1, 2, 3, 4, 5].product  # => 120

Returns:



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# File 'lib/hamster/vector.rb', line 1026

def product(*vectors)
  # if no vectors passed, return "product" as in result of multiplying all items
  return super if vectors.empty?

  vectors.unshift(self)

  if vectors.any?(&:empty?)
    return block_given? ? self : []
  end

  counters = Array.new(vectors.size, 0)

  bump_counters = lambda do
    i = vectors.size-1
    counters[i] += 1
    while counters[i] == vectors[i].size
      counters[i] = 0
      i -= 1
      return true if i == -1 # we are done
      counters[i] += 1
    end
    false # not done yet
  end
  build_array = lambda do
    array = []
    counters.each_with_index { |index,i| array << vectors[i][index] }
    array
  end

  if block_given?
    while true
      yield build_array[]
      return self if bump_counters[]
    end
  else
    result = []
    while true
      result << build_array[]
      return result if bump_counters[]
    end
  end
end

#put(index, item) ⇒ Vector #put(index) {|existing| ... } ⇒ Vector Also known as: set

Return a new Vector with a new value at the given index. If index is greater than the length of the vector, the returned vector will be padded with nils to the correct size.

Overloads:

  • #put(index, item) ⇒ Vector

    Return a new Vector with the item at index replaced by item.

    Examples:

    Hamster::Vector[1, 2, 3, 4].put(2, 99)
# => Hamster::Vector[1, 2, 99, 4]
Hamster::Vector[1, 2, 3, 4].put(-1, 99)
# => Hamster::Vector[1, 2, 3, 99]
Hamster::Vector[].put(2, 99)
# => Hamster::Vector[nil, nil, 99]

    Parameters:

    • item (Object) —

      The object to insert into that position

  • #put(index) {|existing| ... } ⇒ Vector

    Return a new Vector with the item at index replaced by the return value of the block.

    Examples:

    Hamster::Vector[1, 2, 3, 4].put(2) { |v| v * 10 }
# => Hamster::Vector[1, 2, 30, 4]

    Yields:

    • (existing) —

      Once with the existing value at the given index.

Parameters:

  • index (Integer) —

    The index to update. May be negative.

Returns:

Raises:

  • (IndexError) 


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# File 'lib/hamster/vector.rb', line 167

def put(index, item = yield(get(index)))
  raise IndexError, "index #{index} outside of vector bounds" if index < -@size
  index += @size if index < 0
  if index > @size
    suffix = Array.new(index - @size, nil)
    suffix << item
    replace_suffix(@size, suffix)
  else
    update_root(index, item)
  end
end

#rassoc(obj) ⇒ Object

Assumes all elements are nested, indexable collections, and searches through them, comparing obj with the second element of each nested collection. Return the first nested collection which matches, or nil if none is found. Behaviour is undefined when elements do not meet assumptions (i.e. are not indexable collections).

Examples:

v = Hamster::Vector[["A", 10], ["B", 20], ["C", 30]]
v.rassoc(20)  # => ["B", 20]

Parameters:

  • obj (Object) —

    The object to search for

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 1258

def rassoc(obj)
  each do |array|
    next if !array.respond_to?(:[])
    return array if obj == array[1]
  end
  nil
end

#repeated_combination(n) ⇒ self, Enumerator

When invoked with a block, yields all repeated combinations of length n of items from the Vector, and then returns self. A "repeated combination" is one in which any item from the Vector can appear consecutively any number of times.

There is no guarantee about which order the combinations will be yielded in.

If no block is given, an Enumerator is returned instead.

Examples:

v = Hamster::Vector[5, 6, 7, 8]
v.repeated_combination(2) { |c| puts "Combination: #{c}" }

Combination: [5, 5]
Combination: [5, 6]
Combination: [5, 7]
Combination: [5, 8]
Combination: [6, 6]
Combination: [6, 7]
Combination: [6, 8]
Combination: [7, 7]
Combination: [7, 8]
Combination: [8, 8]
# => Hamster::Vector[5, 6, 7, 8]

Returns:

  • (self, Enumerator) 


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# File 'lib/hamster/vector.rb', line 878

def repeated_combination(n)
  return enum_for(:repeated_combination, n) if not block_given?
  if n < 0
    # yield nothing
  elsif n == 0
    yield []
  elsif n == 1
    each { |item| yield [item] }
  elsif @size == 0
    # yield nothing
  else
    combos = lambda do |result,index,remaining|
      while index < @size-1
        if remaining == 1
          yield result.dup << get(index)
        else
          combos[result.dup << get(index), index, remaining-1]
        end
        index += 1
      end
      item = get(index)
      remaining.times { result << item }
      yield result
    end
    combos[[], 0, n]
  end
  self
end

#repeated_permutation(n = @size) ⇒ self, Enumerator

When invoked with a block, yields all repeated permutations of length n of items from the Vector, and then returns self. A "repeated permutation" is one where any item from the Vector can appear any number of times, and in any position (not just consecutively)

If no length n is specified, permutations of all elements will be yielded. There is no guarantee about which order the permutations will be yielded in.

If no block is given, an Enumerator is returned instead.

Examples:

v = Hamster::Vector[5, 6, 7]
v.repeated_permutation(2) { |p| puts "Permutation: #{p}" }

Permutation: [5, 5]
Permutation: [5, 6]
Permutation: [5, 7]
Permutation: [6, 5]
Permutation: [6, 6]
Permutation: [6, 7]
Permutation: [7, 5]
Permutation: [7, 6]
Permutation: [7, 7]
# => Hamster::Vector[5, 6, 7]

Returns:

  • (self, Enumerator) 


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# File 'lib/hamster/vector.rb', line 983

def repeated_permutation(n = @size)
  return enum_for(:repeated_permutation, n) if not block_given?
  if n < 0
    # yield nothing
  elsif n == 0
    yield []
  elsif n == 1
    each { |item| yield [item] }
  else
    result = []
    perms = lambda do |index|
      0.upto(@size-1) do |i|
        result[index] = get(i)
        if index < n-1
          perms[index+1]
        else
          yield result.dup
        end
      end
    end
    perms[0]
  end
  self
end

#reverse ⇒ Vector

Return a new Vector with the same elements as this one, but in reverse order.

Examples:

Hamster::Vector["A", "B", "C"].reverse  # => Hamster::Vector["C", "B", "A"]

Returns:



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# File 'lib/hamster/vector.rb', line 540

def reverse
  self.class.new(((array = to_a).frozen? ? array.reverse : array.reverse!).freeze)
end

#reverse_each(&block) ⇒ self

Call the given block once for each item in the vector, from last to first.

Examples:

Hamster::Vector["A", "B", "C"].reverse_each { |e| puts "Element: #{e}" }

Element: C
Element: B
Element: A

Returns:

  • (self) 


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# File 'lib/hamster/vector.rb', line 446

def reverse_each(&block)
  return enum_for(:reverse_each) unless block_given?
  reverse_traverse_depth_first(@root, @levels, &block)
  self
end

#rindex(obj) ⇒ Integer #rindex {|element| ... } ⇒ Integer

Find the index of an element, starting from the end of the vector. Returns nil if no element is found.

Overloads:

  • #rindex(obj) ⇒ Integer

    Return the index of the last element which is #== to obj.

    Examples:

    v = Hamster::Vector[7, 8, 9, 7, 8, 9]
v.rindex(8) # => 4
  • #rindex {|element| ... } ⇒ Integer

    Return the index of the last element for which the block returns true.

    Examples:

    v = Hamster::Vector[7, 8, 9, 7, 8, 9]
v.rindex { |e| e.even? }  # => 4

    Yields:

    • (element) —

      Once for each element, last to first, until the block returns true.

Returns:

  • (Integer) 


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# File 'lib/hamster/vector.rb', line 1211

def rindex(obj = (missing_arg = true))
  i = @size - 1
  if missing_arg
    if block_given?
      reverse_each { |item| return i if yield item; i -= 1 }
      nil
    else
      enum_for(:rindex)
    end
  else
    reverse_each { |item| return i if item == obj; i -= 1 }
    nil
  end
end

#rotate(count = 1) ⇒ Vector

Return a new Vector with the same elements, but rotated so that the one at index count is the first element of the new vector. If count is positive, the elements will be shifted left, and those shifted past the lowest position will be moved to the end. If count is negative, the elements will be shifted right, and those shifted past the last position will be moved to the beginning.

Examples:

v = Hamster::Vector["A", "B", "C", "D", "E", "F"]
v.rotate(2)   # => Hamster::Vector["C", "D", "E", "F", "A", "B"]
v.rotate(-1)  # => Hamster::Vector["F", "A", "B", "C", "D", "E"]

Parameters:

  • count (Integer) (defaults to: 1) —

    The number of positions to shift items by

Returns:



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# File 'lib/hamster/vector.rb', line 557

def rotate(count = 1)
  return self if (count % @size) == 0
  self.class.new(((array = to_a).frozen? ? array.rotate(count) : array.rotate!(count)).freeze)
end

#sample ⇒ Object

Return a randomly chosen item from this Vector. If the vector is empty, return nil.

Examples:

Hamster::Vector[1, 2, 3, 4, 5].sample  # => 2

Returns:

  • (Object) 


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# File 'lib/hamster/vector.rb', line 1173

def sample
  get(rand(@size))
end

#select {|element| ... } ⇒ Vector Also known as: find_all, keep_if

Return a new Vector containing all elements for which the given block returns true.

Examples:

Hamster::Vector["Bird", "Cow", "Elephant"].select { |e| e.size >= 4 }
# => Hamster::Vector["Bird", "Elephant"]

Yields:

  • (element) —

    Once for each element.

Returns:



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# File 'lib/hamster/vector.rb', line 461

def select
  return enum_for(:select) unless block_given?
  reduce(self.class.empty) { |vector, item| yield(item) ? vector.add(item) : vector }
end

#shift ⇒ Vector

Return a new Vector with the first element removed. If empty, return self.

Examples:

Hamster::Vector["A", "B", "C"].shift  # => Hamster::Vector["B", "C"]

Returns:



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# File 'lib/hamster/vector.rb', line 412

def shift
  delete_at(0)
end

#shuffle ⇒ Vector

Return a new Vector with the same elements as this one, but randomly permuted.

Examples:

Hamster::Vector[1, 2, 3, 4].shuffle  # => Hamster::Vector[4, 1, 3, 2]

Returns:



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# File 'lib/hamster/vector.rb', line 515

def shuffle
  self.class.new(((array = to_a).frozen? ? array.shuffle : array.shuffle!).freeze)
end

#vector.slice(index) ⇒ Object #vector.slice(index, length) ⇒ Vector #vector.slice(index..end) ⇒ Vector Also known as: []

Return specific objects from the Vector. All overloads return nil if the starting index is out of range.

Overloads:

  • #vector.slice(index) ⇒ Object

    Returns a single object at the given index. If index is negative, count backwards from the end.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D", "E", "F"]
v[2]  # => "C"
v[-1] # => "F"
v[6]  # => nil

    Parameters:

    • index (Integer) —

      The index to retrieve. May be negative.

    Returns:

    • (Object)
  • #vector.slice(index, length) ⇒ Vector

    Return a subvector starting at index and continuing for length elements or until the end of the Vector, whichever occurs first.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D", "E", "F"]
v[2, 3]  # => Hamster::Vector["C", "D", "E"]
v[-2, 3] # => Hamster::Vector["E", "F"]
v[20, 1] # => nil

    Parameters:

    • start (Integer) —

      The index to start retrieving items from. May be negative.

    • length (Integer) —

      The number of items to retrieve.

    Returns:

  • #vector.slice(index..end) ⇒ Vector

    Return a subvector starting at index and continuing to index end or the end of the Vector, whichever occurs first.

    Examples:

    v = Hamster::Vector["A", "B", "C", "D", "E", "F"]
v[2..3]    # => Hamster::Vector["C", "D"]
v[-2..100] # => Hamster::Vector["E", "F"]
v[20..21]  # => nil

    Parameters:

    • range (Range) —

      The range of indices to retrieve.

    Returns:



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# File 'lib/hamster/vector.rb', line 312

def slice(arg, length = (missing_length = true))
  if missing_length
    if arg.is_a?(Range)
      from, to = arg.begin, arg.end
      from += @size if from < 0
      to   += @size if to < 0
      to   += 1     if !arg.exclude_end?
      length = to - from
      length = 0 if length < 0
      subsequence(from, length)
    else
      get(arg)
    end
  else
    arg += @size if arg < 0
    subsequence(arg, length)
  end
end

#sort ⇒ Vector #sort {|a, b| ... } ⇒ Vector

Return a new Vector with the same items, but sorted.

Overloads:

  • #sort ⇒ Vector

    Compare elements with their natural sort key (#<=>).

    Examples:

    Hamster::Vector["Elephant", "Dog", "Lion"].sort
# => Hamster::Vector["Dog", "Elephant", "Lion"]
  • #sort {|a, b| ... } ⇒ Vector

    Uses the block as a comparator to determine sorted order.

    Examples:

    Hamster::Vector["Elephant", "Dog", "Lion"].sort { |a,b| a.size <=> b.size }
# => Hamster::Vector["Dog", "Lion", "Elephant"]

    Yields:

    • (a, b) —

      Any number of times with different pairs of elements.

    Yield Returns:

    • (Integer) —

      Negative if the first element should be sorted lower, positive if the latter element, or 0 if equal.

Returns:



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# File 'lib/hamster/vector.rb', line 660

def sort
  self.class.new(super)
end

#sort_by {|element| ... } ⇒ Vector

Return a new Vector with the same items, but sorted. The sort order is determined by mapping the items through the given block to obtain sort keys, and then sorting the keys according to their natural sort order (#<=>).

Examples:

Hamster::Vector["Elephant", "Dog", "Lion"].sort_by { |e| e.size }
# => Hamster::Vector["Dog", "Lion", "Elephant"]

Yields:

  • (element) —

    Once for each element.

Yield Returns:

  • a sort key object for the yielded element.

Returns:



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# File 'lib/hamster/vector.rb', line 676

def sort_by
  self.class.new(super)
end

#take(n) ⇒ Vector

Return only the first n elements in a new Vector.

Examples:

Hamster::Vector["A", "B", "C", "D", "E", "F"].take(4)
# => Hamster::Vector["A", "B", "C", "D"]

Parameters:

  • n (Integer) —

    The number of elements to retain

Returns:



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# File 'lib/hamster/vector.rb', line 704

def take(n)
  return self if n >= @size
  self.class.new(super)
end

#take_while ⇒ Vector, Enumerator

Gather elements up to, but not including, the first element for which the block returns nil or false, and return them in a new Vector. If no block is given, an Enumerator is returned instead.

Examples:

Hamster::Vector[1, 3, 5, 7, 6, 4, 2].take_while { |e| e < 5 }
# => Hamster::Vector[1, 3]

Returns:



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# File 'lib/hamster/vector.rb', line 732

def take_while
  return enum_for(:take_while) if not block_given?
  self.class.new(super)
end

#to_a ⇒ Array Also known as: to_ary

Return an Array with the same elements, in the same order. The returned Array may or may not be frozen.

Returns:

  • (Array) 


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# File 'lib/hamster/vector.rb', line 1270

def to_a
  if @levels == 0
    # When initializing a Vector with 32 or less items, we always make
    # sure @root is frozen, so we can return it directly here
    @root
  else
    flatten_node(@root, @levels * BITS_PER_LEVEL, [])
  end
end

#transpose ⇒ Vector

Assume all elements are vectors or arrays and transpose the rows and columns. In other words, take the first element of each nested vector/array and gather them together into a new Vector. Do likewise for the second, third, and so on down to the end of each nested vector/array. Gather all the resulting Vectors into a new Vector and return it.

This operation is closely related to #zip. The result is almost the same as calling #zip on the first nested vector/array with the others supplied as arguments.

Examples:

Hamster::Vector[["A", 10], ["B", 20], ["C", 30]].transpose
# => Hamster::Vector[Hamster::Vector["A", "B", "C"], Hamster::Vector[10, 20, 30]]

Returns:

Raises:

  • (IndexError) —

    if elements are not of the same size.

  • (TypeError) —

    if an element can not be implicitly converted to an array (using #to_ary)



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# File 'lib/hamster/vector.rb', line 1086

def transpose
  return self.class.empty if empty?
  result = Array.new(first.size) { [] }

  0.upto(@size-1) do |i|
    source = get(i)
    if source.size != result.size
      raise IndexError, "element size differs (#{source.size} should be #{result.size})"
    end

    0.upto(result.size-1) do |j|
      result[j].push(source[j])
    end
  end

  result.map! { |a| self.class.new(a) }
  self.class.new(result)
rescue NoMethodError
  if any? { |x| !x.respond_to?(:size) || !x.respond_to?(:[]) }
    bad = find { |x| !x.respond_to?(:size) || !x.respond_to?(:[]) }
    raise TypeError, "'#{bad.inspect}' must respond to #size and #[] to be transposed"
  else
    raise
  end
end

#uniq(&block) ⇒ Vector

Return a new Vector with no duplicate elements, as determined by #hash and #eql?. For each group of equivalent elements, only the first will be retained.

Examples:

Hamster::Vector["A", "B", "C", "B"].uniq      # => Hamster::Vector["A", "B", "C"]
Hamster::Vector["a", "A", "b"].uniq(&:upcase) # => Hamster::Vector["a", "b"]

Returns:



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# File 'lib/hamster/vector.rb', line 527

def uniq(&block)
  array = self.to_a
  return self.class.new(array.uniq(&block).freeze) if array.frozen?
  return self.class.new(array.freeze) if array.uniq!(&block)
  self
end

#unshift(object) ⇒ Vector

Return a new Vector with object inserted before the first element, moving the other elements upwards.

Examples:

Hamster::Vector["A", "B"].unshift("Z")
# => Hamster::Vector["Z", "A", "B"]

Parameters:

  • object (Object) —

    The value to prepend

Returns:



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# File 'lib/hamster/vector.rb', line 401

def unshift(object)
  insert(0, object)
end

#values_at(*indices) ⇒ Vector

Return a new Vector with only the elements at the given indices, in the order specified by indices. If any of the indices do not exist, nils will appear in their places.

Examples:

v = Hamster::Vector["A", "B", "C", "D", "E", "F"]
v.values_at(2, 4, 5)   # => Hamster::Vector["C", "E", "F"]

Parameters:

  • indices (Array) —

    The indices to retrieve and gather into a new Vector

Returns:



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# File 'lib/hamster/vector.rb', line 1187

def values_at(*indices)
  self.class.new(indices.map { |i| get(i) }.freeze)
end

#zip(*others) ⇒ Vector #zip(*others) {|pair| ... } ⇒ nil

Combine two vectors by "zipping" them together. others should be arrays and/or vectors. The corresponding elements from this Vector and each of others (that is, the elements with the same indices) will be gathered into arrays.

If others contains fewer elements than this vector, nil will be used for padding.

Examples:

v1 = Hamster::Vector["A", "B", "C"]
v2 = Hamster::Vector[1, 2]
v1.zip(v2)
# => Hamster::Vector[["A", 1], ["B", 2], ["C", nil]]

Overloads:

  • #zip(*others) ⇒ Vector

    Return a new vector containing the new arrays.

    Returns:

  • #zip(*others) {|pair| ... } ⇒ nil

    Yields:

    • (pair) —

      once for each array

    Returns:

    • (nil)

Parameters:

  • others (Array) —

    The arrays/vectors to zip together with this one

Returns:



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# File 'lib/hamster/vector.rb', line 631

def zip(*others)
  if block_given?
    super
  else
    self.class.new(super)
  end
end