猪-过滤器或如何进入袋子或元组的侧面

Question

AS you can see we can apply filter to the first one because, we can used aggregate on the temperature. Now how do we apply the second filter on STRINGS?

We are only trying to filter e with conditions clear and partly cloudy.

Weather = LOAD 'hdfs:/home/hduser/final/Weather.csv' USING PigStorage(',');
A = FOREACH Weather GENERATE (int)$0 AS year, (int)$1 AS month, (int)$2 AS day, (int)$4 AS temp, $14 AS cond, (double)$5 as dewpoint , (double)$10 as wind;


group_by_day = GROUP A BY (year,month,day);

Schema:

   {day: (year: int,month: int, day: int), temperature {(temp: int)},                   

   condition: {cond: bytearray)}, dewPoint: {(dewpoint: double)} windSpeed:

   {(wind: double)}}

Answer 1

You have to cast cond as chararray in the below statement.Since you have not specified the datatype in your load statement,all fields will be loaded as bytearray.That is the default datatype chosen by PigStorage.

A = FOREACH Weather GENERATE (int)$0 AS year, (int)$1 AS month, (int)$2 AS day, (int)$4 AS temp, (chararray)$14 AS cond, (double)$5 as dewpoint , (double)$10 as wind;

EDIT

I was able to get the results by use BagToString function.You can do the filtering in 1 step iteslf.

D = FILTER C BY (MIN(temperature) >= 60 AND MAX(temperature) <= 79) AND (BagToString(condition) == 'clear' OR BagToString(condition) == 'partly cloudy');

Or in your case

f = FILTER e BY BagToString(condition) == 'clear' OR BagToString(condition) == 'partly cloudy';