In the previous post<\/a> we look at how to group records and we also found average volume of stocks from year 2003. In this post we will see how to order or sort records using Apache Pig.<\/p>\nFirst lets load, group and find the average volume of stocks symbol from year 2003.<\/p>\n
grunt> stocks = LOAD '\/user\/hirw\/input\/stocks' USING PigStorage(',') as (exchange:chararray, symbol:chararray, date:datetime, open:float, high:float, low:float, close:float, volume:int, adj_close:float);\n\ngrunt> filter_by_yr = FILTER stocks by GetYear(date) == 2003;\n\ngrunt> grp_by_sym = GROUP filter_by_yr BY symbol;\n\ngrunt> avg_volume = FOREACH grp_by_sym GENERATE group, ROUND(AVG(filter_by_yr.volume)) as avgvolume;<\/pre>\n\u00a0Ordering Records<\/h2>\n
Use the ORDER operator to order the records. By default records are ordered in ascending order. Use DESC to order records in descending order.<\/p>\n
grunt>\u00a0avg_vol_ordered = ORDER avg_volume BY avgvolume DESC;<\/pre>\nWe can also choose to perform ordering with multiple columns . In the below instruction, the records will be ordered by symbol and the volume. In the below instruction group <\/span>\u00a0refers to the symbol column.<\/p>\ngrunt>\u00a0avg_vol_ordered = ORDER avg_volume BY group, avgvolume DESC;<\/pre>\nDisplay Results<\/h2>\ngrunt> DUMP avg_vol_ordered;<\/pre>\n\u00a0See It In Action<\/h2>\n