giuse/data_modeler

class DataModeler::Dataset

  # Returns an instance of the DataModeler::Dataset::Accessor class
  # @param args [Hash] Accessor class parameters
  # @return [Accessor] initialized instance of Accessor class
  def self.new *args
    Accessor.new *args
  end

  ### HELPER MODULES

  # Converts between time and indices for referencing data lines
  module ConvertingTimeAndIndices
    # Returns the time for a given index
    # @param [Integer] idx row index
    # @return [type of `data[:time]`]
    def time idx
      data[:time][idx]
    end

    # Returns the index for a given time
    # @param [time] time
    # @return [Integer] row index
    def idx time
      # TODO: optimize with `from:`
      # TODO: test corner case when index not found
      # find index of first above time
      idx = data[:time].index { |t| t > time }
      # if index not found: all data is below time, "first above" is outofbound
      idx ||= nrows
      # if first above time is 0: there is no element with that time
      raise TimeNotFoundError, "Time not found: #{time}" if idx.zero?
      # return index of predecessor (last below time)
      idx-1
    end
  end

  # Provides `#each` (which can return an `Iterator`) and `#to_a` based on `#next`
  module IteratingBasedOnNext
    # Yields on each [inputs, targets] pair.
    # @return [nil|Iterator] `block_given? ? nil : Iterator`
    def each
      reset_iteration
      return enum_for(:each) unless block_given?
      loop { yield self.next }
      nil
    end

    # Yields on each `[inputs, targets]` pair, collecting the input.
    # @return [Array|Iterator] `block_given? ? nil : Iterator`
    def map
      reset_iteration
      return enum_for(:collect) unless block_given?
      [].tap { |ret| loop { ret << yield(self.next) } }
    end

    # @see #collect
    alias_method :collect, :map

    # @return [Array]
    def to_a
      each.to_a
    end
  end
end