按部门id分组，计算每个员工记录的平均工资，并选择工资高于平均工资的员工。
代码段：

inp_data = LOAD 'Assignment_1_Input.log' USING PigStorage('\t') as (id:int,name:chararray,age:int,salary:int,deptid:int);
inp_data_fmt = FOREACH(GROUP inp_data BY deptid) GENERATE FLATTEN(inp_data), AVG(inp_data.salary) AS avg_salary;
req_data = FILTER inp_data_fmt BY salary > avg_salary;
DUMP req_data;

JOIN a和c由deptid、grpid和 FILTER 其中薪资>grpavgsal

A = LOAD 'Assignment_1_Input.log' USING PigStorage('\t') as (id:int,name:chararray,age:int,salary:int,deptid:int);
B = GROUP A by deptid;
STORE B INTO 'Assign1GrpByNew';
C = FOREACH B GENERATE group as grpId,AVG(A.salary) as grpAvgSal;

D = JOIN A BY deptid,C BY grpId;
E = FILTER D BY (A::salary > C::grpAvgSal);
DUMP E;