define Quartile datafu.pig.stats.Quantile('0.0','0.25','0.5','0.75','1.0');

temperature = LOAD 'temperature.txt' AS (id:chararray, temp:double);

temperature = GROUP temperature BY id;

temperature_quartiles = FOREACH temperature {
  sorted = ORDER temperature by temp; -- must be sorted
  GENERATE group as id, Quartile(sorted.temp) as quartiles;
}

DUMP temperature_quartiles