Class: DataFrame

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

Overview

This allows me to have named columns and optionally named rows in a data frame, to work calculations (usually on the columns), to transpose the matrix and store the transposed matrix until the object is tainted.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*labels) ⇒ DataFrame

Returns a new instance of DataFrame.



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# File 'lib/data_frame.rb', line 81

def initialize(*labels)
  @labels = labels.map {|e| e.to_underscore_sym }
  @items = TransposableArray.new
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(sym, *args, &block) ⇒ Object 



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

def method_missing(sym, *args, &block)
  if self.labels.include?(sym)
    render_column(sym)
  elsif self.row_labels.include?(sym)
    render_row(sym)
  elsif @items.respond_to?(sym)
    @items.send(sym, *args, &block)
  else
    super
  end
end

Instance Attribute Details

#items ⇒ Object (readonly) Also known as: rows

The items stored in the frame



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# File 'lib/data_frame.rb', line 79

def items
  @items
end

#labels ⇒ Object (readonly) Also known as: variables

The labels of the data items



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# File 'lib/data_frame.rb', line 75

def labels
  @labels
end

Class Method Details

.from_csv(obj, opts = {}) ⇒ Object

This is the neatest part of this neat gem. DataFrame.from_csv can be called in a lot of ways: DataFrame.from_csv(csv_contents) DataFrame.from_csv(filename) DataFrame.from_csv(url) If you need to define converters for FasterCSV, do it before calling this method: FasterCSV::Converters = lambda{|f| f == ‘foo’ ? ‘bar’ : ‘foo’} DataFrame.from_csv(‘example.com/my_special_url.csv’, :converters => :special) This returns bar where ‘foo’ was found and ‘foo’ everywhere else.



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# File 'lib/data_frame.rb', line 40

def from_csv(obj, opts={})
  labels, table = infer_csv_contents(obj, opts)
  return nil unless labels and table
  df = new(*labels)
  df.import(table)
  df
end

Instance Method Details

#add_item(item) ⇒ Object Also known as: add 



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# File 'lib/data_frame.rb', line 86

def add_item(item)
  self.items << item
end

#columns(reset = false) ⇒ Object Also known as: to_hash, to_dictionary

The columns as a Dictionary or Hash This is cached, call columns(true) to reset the cache.



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# File 'lib/data_frame.rb', line 111

def columns(reset=false)
  @columns = nil if reset
  return @columns if @columns
  
  container = defined?(Dictionary) ? Dictionary.new : Hash.new
  i = 0
  
  @columns = @items.transpose.inject(container) do |cont, col|
    cont[@labels[i]] = col
    i += 1
    cont
  end
end

#drop!(label) ⇒ Object 



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# File 'lib/data_frame.rb', line 145

def drop!(label)
  i = self.labels.index(label)
  return nil unless i
  self.items.each do |item|
    item.delete_at(i)
  end
  self.labels.delete_at(i)
  true
end

#import(rows) ⇒ Object

Loads a batch of rows. Expects an array of arrays, else you don’t know what you have.



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# File 'lib/data_frame.rb', line 68

def import(rows)
  rows.each do |row|
    self.add_item(row)
  end
end

#render_column(sym) ⇒ Object 



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# File 'lib/data_frame.rb', line 100

def render_column(sym)
  i = @labels.index(sym)
  return nil unless i
  @items.transpose[i]
end

#render_row(sym) ⇒ Object 



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# File 'lib/data_frame.rb', line 127

def render_row(sym)
  i = self.row_labels.index(sym)
  return nil unless i
  @items[i]
end

#row_labels ⇒ Object 



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# File 'lib/data_frame.rb', line 91

def row_labels
  @row_labels ||= []
end

#row_labels=(ary) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/data_frame.rb', line 95

def row_labels=(ary)
  raise ArgumentError, "Row labels must be an array" unless ary.is_a?(Array)
  @row_labels = ary
end