Class: Rover::DataFrame

Inherits:
Object
  • Object
show all
Defined in:
lib/rover/data_frame.rb

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ DataFrame

Returns a new instance of DataFrame.



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# File 'lib/rover/data_frame.rb', line 3

def initialize(*args)
  data, options = process_args(args)

  @vectors = {}
  types = options[:types] || {}

  if data.is_a?(DataFrame)
    data.vectors.each do |k, v|
      @vectors[k] = v
    end
  elsif data.is_a?(Hash)
    data.to_h.each do |k, v|
      @vectors[k] =
        if v.respond_to?(:to_a)
          Vector.new(v, type: types[k])
        else
          v
        end
    end

    # handle scalars
    size = @vectors.values.find { |v| v.is_a?(Vector) }&.size || 1
    @vectors.each_key do |k|
      @vectors[k] = to_vector(@vectors[k], size: size, type: types[k])
    end
  elsif data.is_a?(Array)
    vectors = {}
    raise ArgumentError, "Array elements must be hashes" unless data.all? { |d| d.is_a?(Hash) }
    keys = data.flat_map(&:keys).uniq
    keys.each do |k|
      vectors[k] = []
    end
    data.each do |d|
      keys.each do |k|
        vectors[k] << d[k]
      end
    end
    vectors.each do |k, v|
      @vectors[k] = to_vector(v, type: types[k])
    end
  elsif defined?(ActiveRecord) && (data.is_a?(ActiveRecord::Relation) || (data.is_a?(Class) && data < ActiveRecord::Base) || data.is_a?(ActiveRecord::Result))
    result = data.is_a?(ActiveRecord::Result) ? data : data.connection_pool.with_connection { |c| c.select_all(data.all.to_sql) }
    result.columns.each_with_index do |k, i|
      @vectors[k] = to_vector(result.rows.map { |r| r[i] }, type: types[k])
    end
  else
    raise ArgumentError, "Cannot cast to data frame: #{data.class.name}"
  end

  # check keys
  @vectors.each_key do |k|
    check_key(k)
  end

  # check sizes
  sizes = @vectors.values.map(&:size).uniq
  if sizes.size > 1
    raise ArgumentError, "Different sizes: #{sizes}"
  end
end

Instance Method Details

#+(other) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 368

def +(other)
  dup.concat(other)
end

#==(other) ⇒ Object

don’t check types



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# File 'lib/rover/data_frame.rb', line 409

def ==(other)
  size == other.size &&
  keys == other.keys &&
  keys.all? { |k| self[k].to_numo == other[k].to_numo }
end

#[](where) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 64

def [](where)
  if (where.is_a?(Vector) && where.to_numo.is_a?(Numo::Bit)) || where.is_a?(Numeric) || where.is_a?(Range) || (where.is_a?(Array) && where.all? { |v| v.is_a?(Integer) })
    new_vectors = {}
    @vectors.each do |k, v|
      new_vectors[k] = v[where]
    end
    DataFrame.new(new_vectors)
  elsif where.is_a?(Array)
    # multiple columns
    df = DataFrame.new
    where.each do |k|
      check_column(k)
      df[k] = @vectors[k]
    end
    df
  else
    # single column
    @vectors[where]
  end
end

#[]=(k, v) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/rover/data_frame.rb', line 102

def []=(k, v)
  check_key(k)
  v = to_vector(v, size: size)
  raise ArgumentError, "Size mismatch (given #{v.size}, expected #{size})" if @vectors.any? && v.size != size
  @vectors[k] = v
end

#any? ⇒ Boolean

should this check for columns as well?

Returns:

  • (Boolean) 


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# File 'lib/rover/data_frame.rb', line 116

def any?
  size > 0
end

#clear ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 125

def clear
  @vectors.clear
end

#concat(other) ⇒ Object

in-place, like Array#concat TODO make more performant

Raises:

  • (ArgumentError) 


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# File 'lib/rover/data_frame.rb', line 374

def concat(other)
  raise ArgumentError, "Must be a data frame" unless other.is_a?(DataFrame)

  size = self.size
  vectors.each do |k, v|
    @vectors[k] = Vector.new(v.to_a + (other[k] ? other[k].to_a : [nil] * other.size))
  end
  (other.vector_names - vector_names).each do |k|
    @vectors[k] = Vector.new([nil] * size + other[k].to_a)
  end
  self
end

#deep_dup ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 360

def deep_dup
  df = DataFrame.new
  @vectors.each do |k, v|
    df[k] = v.dup
  end
  df
end

#delete(key) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 150

def delete(key)
  @vectors.delete(key)
end

#each_row ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 85

def each_row
  return enum_for(:each_row) unless block_given?

  size.times do |i|
    yield @vectors.map { |k, v| [k, v[i]] }.to_h
  end
end

#empty? ⇒ Boolean

should this check for columns as well?

Returns:

  • (Boolean) 


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# File 'lib/rover/data_frame.rb', line 121

def empty?
  size == 0
end

#except(*keys) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 154

def except(*keys)
  dup.except!(*keys)
end

#except!(*keys) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 158

def except!(*keys)
  keys.each do |key|
    delete(key)
  end
  self
end

#first(n = 1) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 177

def first(n = 1)
  new_vectors = {}
  @vectors.each do |k, v|
    new_vectors[k] = v.first(n)
  end
  DataFrame.new(new_vectors)
end

#group(*columns) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 349

def group(*columns)
  Group.new(self, columns.flatten)
end

#head(n = 5) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 169

def head(n = 5)
  first(n)
end

#include?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rover/data_frame.rb', line 165

def include?(key)
  @vectors.include?(key)
end

#inner_join(other, on: nil) ⇒ Object

see join for options



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# File 'lib/rover/data_frame.rb', line 399

def inner_join(other, on: nil)
  join(other, on: on, how: "inner")
end

#inspect ⇒ Object Also known as: to_s

TODO handle long text better



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# File 'lib/rover/data_frame.rb', line 299

def inspect
  return "#<Rover::DataFrame>" if keys.empty?

  lines = []
  line_start = 0
  spaces = 2

  summarize = size >= 30

  @vectors.each do |k, v|
    v = summarize ? v.first(5).to_a + ["..."] + v.last(5).to_a : v.to_a
    width = ([k] + v).map(&:to_s).map(&:size).max
    width = 3 if width < 3

    if lines.empty? || lines[-2].map { |l| l.size + spaces }.sum + width > 120
      line_start = lines.size
      lines << []
      v.size.times do |i|
        lines << []
      end
      lines << []
    end

    lines[line_start] << "%#{width}s" % k.to_s
    v.each_with_index do |v2, i|
      lines[line_start + 1 + i] << "%#{width}s" % v2.to_s
    end
  end

  lines.pop
  lines.map { |l| l.join(" " * spaces) }.join("\n")
end

#keys ⇒ Object Also known as: names, vector_names 



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# File 'lib/rover/data_frame.rb', line 133

def keys
  @vectors.keys
end

#last(n = 1) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 185

def last(n = 1)
  new_vectors = {}
  @vectors.each do |k, v|
    new_vectors[k] = v.last(n)
  end
  DataFrame.new(new_vectors)
end

#left_join(other, on: nil) ⇒ Object

see join for options



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# File 'lib/rover/data_frame.rb', line 404

def left_join(other, on: nil)
  join(other, on: on, how: "left")
end

#merge(other) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 387

def merge(other)
  dup.merge!(other)
end

#merge!(other) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 391

def merge!(other)
  other.vectors.each do |k, v|
    self[k] = v
  end
  self
end

#one_hot(drop: false) ⇒ Object

TODO raise error when collision



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# File 'lib/rover/data_frame.rb', line 220

def one_hot(drop: false)
  df = DataFrame.new
  vectors.each do |k, v|
    if v.to_numo.is_a?(Numo::RObject)
      df.merge!(v.one_hot(drop: drop, prefix: "#{k}_"))
    else
      df[k] = v
    end
  end
  df
rescue ArgumentError => e
  if e.message == "All elements must be strings"
    # better error message
    raise ArgumentError, "All elements must be numeric or strings"
  end
  raise e
end

#plot(x = nil, y = nil, type: nil, group: nil, stacked: nil) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/rover/data_frame.rb', line 415

def plot(x = nil, y = nil, type: nil, group: nil, stacked: nil)
  require "vega"

  raise ArgumentError, "Must specify columns" if keys.size != 2 && (!x || !y)
  x ||= keys[0]
  y ||= keys[1]
  type ||= begin
    if self[x].numeric? && self[y].numeric?
      "scatter"
    elsif types[x] == :object && self[y].numeric?
      "column"
    else
      raise "Cannot determine type. Use the type option."
    end
  end
  data = self[group.nil? ? [x, y] : [x, y, group]]

  case type
  when "line", "area"
    x_type =
      if data[x].numeric?
        "quantitative"
      elsif data[x].all? { |v| v.is_a?(Date) || v.is_a?(Time) }
        "temporal"
      else
        "nominal"
      end

    scale = x_type == "temporal" ? {type: "utc"} : {}
    encoding = {
      x: {field: x, type: x_type, scale: scale},
      y: {field: y, type: "quantitative"}
    }
    encoding[:color] = {field: group} if group

    Vega.lite
      .data(data)
      .mark(type: type, tooltip: true, interpolate: "cardinal", point: {size: 60})
      .encoding(encoding)
      .config(axis: {labelFontSize: 12})
  when "pie"
    raise ArgumentError, "Cannot use group option with pie chart" unless group.nil?

    Vega.lite
      .data(data)
      .mark(type: "arc", tooltip: true)
      .encoding(
        color: {field: x, type: "nominal", sort: "none", axis: {title: nil}, legend: {labelFontSize: 12}},
        theta: {field: y, type: "quantitative"}
      )
      .view(stroke: nil)
  when "column"
    encoding = {
      x: {field: x, type: "nominal", sort: "none", axis: {labelAngle: 0}},
      y: {field: y, type: "quantitative"}
    }
    if group
      encoding[:color] = {field: group}
      encoding[:xOffset] = {field: group} unless stacked
    end

    Vega.lite
      .data(data)
      .mark(type: "bar", tooltip: true)
      .encoding(encoding)
      .config(axis: {labelFontSize: 12})
  when "bar"
    encoding = {
      # TODO determine label angle
      y: {field: x, type: "nominal", sort: "none", axis: {labelAngle: 0}},
      x: {field: y, type: "quantitative"}
    }
    if group
      encoding[:color] = {field: group}
      encoding[:yOffset] = {field: group} unless stacked
    end

    Vega.lite
      .data(data)
      .mark(type: "bar", tooltip: true)
      .encoding(encoding)
      .config(axis: {labelFontSize: 12})
  when "scatter"
    encoding = {
      x: {field: x, type: "quantitative", scale: {zero: false}},
      y: {field: y, type: "quantitative", scale: {zero: false}},
      size: {value: 60}
    }
    encoding[:color] = {field: group} if group

    Vega.lite
      .data(data)
      .mark(type: "circle", tooltip: true)
      .encoding(encoding)
      .config(axis: {labelFontSize: 12})
  else
    raise ArgumentError, "Invalid type: #{type}"
  end
end

#rename(mapping) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 139

def rename(mapping)
  mapping.each_key do |k|
    check_column(k)
  end
  # use transform_keys! to preserve order
  @vectors.transform_keys! do |k|
    mapping[k] || k
  end
  self
end

#sample(*args, **kwargs) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 193

def sample(*args, **kwargs)
  # TODO make more efficient
  indexes = (0...size).to_a.sample(*args, **kwargs)
  self[indexes]
end

#shape ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 129

def shape
  [size, @vectors.size]
end

#size ⇒ Object Also known as: length, count 



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# File 'lib/rover/data_frame.rb', line 109

def size
  @vectors.values.first&.size || 0
end

#sort_by(&block) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 345

def sort_by(&block)
  dup.sort_by!(&block)
end

#sort_by! ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 333

def sort_by!
  indexes =
    size.times.sort_by do |i|
      yield @vectors.map { |k, v| [k, v[i]] }.to_h
    end

  @vectors.each do |k, v|
    self[k] = v.to_numo.at(indexes)
  end
  self
end

#tail(n = 5) ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 173

def tail(n = 5)
  last(n)
end

#to_a ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 199

def to_a
  a = []
  each_row do |row|
    a << row
  end
  a
end

#to_csv ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 238

def to_csv
  require "csv"
  CSV.generate do |csv|
    csv << keys
    numo = vectors.values.map(&:to_numo)
    size.times do |i|
      csv << numo.map { |n| n[i] }
    end
  end
end

#to_h ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 207

def to_h
  hsh = {}
  @vectors.each do |k, v|
    hsh[k] = v.to_a
  end
  hsh
end

#to_html ⇒ Object

for IRuby



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# File 'lib/rover/data_frame.rb', line 288

def to_html
  require "iruby"
  if size > 7
    # pass 8 rows so maxrows is applied
    IRuby::HTML.table((self[0..4] + self[-4..-1]).to_h, maxrows: 7)
  else
    IRuby::HTML.table(to_h)
  end
end

#to_numo ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 215

def to_numo
  Numo::NArray.column_stack(vectors.values.map(&:to_numo))
end

#to_parquet ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 249

def to_parquet
  require "parquet"

  schema = {}
  types.each do |name, type|
    schema[name] =
      case type
      when :int64
        :int64
      when :uint64
        :uint64
      when :float64
        :double
      when :float32
        :float
      when :bool
        :boolean
      when :object
        if @vectors[name].all? { |v| v.is_a?(String) }
          :string
        else
          raise "Unknown type"
        end
      else
        type
      end
  end
  # TODO improve performance
  raw_records = []
  size.times do |i|
    raw_records << @vectors.map { |_, v| v[i] }
  end
  table = Arrow::Table.new(schema, raw_records)
  buffer = Arrow::ResizableBuffer.new(1024)
  table.save(buffer, format: :parquet)
  buffer.data.to_s
end

#types ⇒ Object 



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# File 'lib/rover/data_frame.rb', line 98

def types
  @vectors.map { |k, v| [k, v.type] }.to_h
end

#vectors ⇒ Object

dup to prevent direct modification of keys



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# File 'lib/rover/data_frame.rb', line 94

def vectors
  @vectors.dup
end