How can I find the Maximum Year in a given dataset using PIG?

Question

Suppose I have the following dataset :-

Year Temp

1974 48
1974 48
1991 56
1983 89
1993 91
1938 41
1938 56
1941 93
1983 87

I want my final answer to be 93 ( Pertaining to the year 1941). I am able to find the Maximum temperature for each year(Say 1941-93) but unable to find only the maximum. Any suggestions are appreciated.

Thanks,

Answer 1

You can solve this problem in two ways.

Option1: Using (Group ALL + MAX)

A = LOAD 'input' USING PigStorage() AS (Year:int,Temp:int);
B = GROUP A ALL;
C = FOREACH B GENERATE MAX(A.Temp);
DUMP C;

Output:

(93)

Option2: Using (ORDER and LIMIT)

A = LOAD 'input' USING PigStorage() AS (Year:int,Temp:int);
B = ORDER A BY Temp DESC;
C = LIMIT B 1;
D = FOREACH C GENERATE Temp;
DUMP D;

Output:

(93)