Class: UniqueCountReduce

Inherits:

ReduceBase

• Object
• Stage
• ReduceBase
• UniqueCountReduce

Defined in:

lib/mrtoolkit.rb

Overview

Reducer counts within each unique value of the first field. Outputs one line of counts for each unique value of the first field.

Instance Attribute Summary

Attributes inherited from Stage

#errors, #in_fields, #in_sep, #out_fields, #out_sep

Instance Method Summary

• #declare ⇒ Object
• #initialize(*args) ⇒ UniqueCountReduce constructor

  A new instance of UniqueCountReduce.

• #process_each(input, output) ⇒ Object
• #process_init(input, output) ⇒ Object
• #process_term(dummy, output) ⇒ Object

Methods inherited from ReduceBase

#process, #process_begin, #process_end, #process_end_internal, #process_internal, #run

Methods inherited from Stage

#catch_errors, #copy_struct, #emit, #emit_separator, #field, #field_separator, #new_input, #new_output, #prepare, #process_step, #write_out

Constructor Details

#initialize(*args) ⇒ UniqueCountReduce

Returns a new instance of UniqueCountReduce.

# File 'lib/mrtoolkit.rb', line 422

def initialize(*args)
  if args[0]
    @m = args[0].to_i - 1
  else
    @m = -1
  end
end

Instance Method Details

#declare ⇒ Object

# File 'lib/mrtoolkit.rb', line 430

def declare
  field :unique
  (0..@m).each {|i| field "extra#{i}"}

  emit :value
  emit :count
  (0..@m).each {|i| emit "extra#{i}"}
end

#process_each(input, output) ⇒ Object

# File 'lib/mrtoolkit.rb', line 443

def process_each(input, output)
  @count += 1
  (0..@m).each {|i| @extra[i] = input[i+1]}
  nil
end

#process_init(input, output) ⇒ Object

# File 'lib/mrtoolkit.rb', line 438

def process_init(input, output)
  @count = 0
  @extra = Array.new(@m+1)
  nil
end

#process_term(dummy, output) ⇒ Object

# File 'lib/mrtoolkit.rb', line 448

def process_term(dummy, output)
  output.value = @last
  output.count = @count
  (0..@m).each {|i| output[i+2] = @extra[i]}
  output
end