Example: Count Word Occurrences


/input_key: document name

//input_value: document contents

map(String input_key, String input_value):

  for each word w in input_value:

    EmitIntermediate(w,"1");



//output_key: a word

//output_values: al list of counts

reduce(String output_key, Iterator intermediate_values):

  in result = 0;

  for each v in intermediate_values:

    result+= ParseInt(v)

  Emit(AsString(result))