Class: SumReduce

Inherits:
ReduceBase show all
Defined in:
lib/mrtoolkit.rb

Overview

Reducer sums given fields Specify how many fields to sum (default 1). May optionally specify how many initial fields to skip Outputs one line of sums

Instance Attribute Summary

Attributes inherited from Stage

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

Instance Method Summary collapse

Methods inherited from ReduceBase

#process_each, #process_end_internal, #process_init, #process_internal, #process_term, #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) ⇒ SumReduce

Returns a new instance of SumReduce.



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# File 'lib/mrtoolkit.rb', line 343

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

Instance Method Details

#declare ⇒ Object 



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# File 'lib/mrtoolkit.rb', line 355

def declare
  (0..@m).each {|i| field "skip#{i}"}
  (0..@n).each {|i| field "count#{i}"}

  (0..@n).each {|i| emit "sum#{i}"}
end

#process(input, output) ⇒ Object 



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# File 'lib/mrtoolkit.rb', line 366

def process(input, output)
  (0..@n).each {|i| @sum[i] += input[i+@m+1].to_f}
  nil
end

#process_begin(dummy, output) ⇒ Object 



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# File 'lib/mrtoolkit.rb', line 362

def process_begin(dummy, output)
  @sum = Array.new(@n+1, 0)
  nil
end

#process_end(dummy, output) ⇒ Object 



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# File 'lib/mrtoolkit.rb', line 370

def process_end(dummy, output)
  (0..@n).each {|i| output[i] = @sum[i]}
  output
end