在豬中創建一個龐大的過濾器

Question

我有這段代碼。

large = load 'a super large file' 

CC = FILTER large BY $19 == 'abc OR $20 == 'abc' 
OR $19 == 'def' or $20 == 'def' ....; 

或條件的數量可能會上升到100甚至數千。

有沒有更好的方法來做到這一點？

Answer 1

是的，將這些條件放在另一個文件中。將它加載到一個關係中，並將兩個關係連接到該列上。如果必須在多列上過濾，則創建與條件一樣多的過濾器文件。下面是2列

large = load 'a super large file' 
filter1 = load 'file with values needed to compare with $19'; 
filter2 = load 'file with values needed to compare with $20'; 
f1 = JOIN large BY $19,filter1 BY $0; 
f2 = JOIN large BY $20,filter2 BY $0; 
final = UNION f1,f2; 
DUMP final; 

你或許可以使用多列1個過濾文件和加入那些得到不同的過濾效果，然後就工會的關係。

large = load 'a super large file' 
filter_file = load 'file with values in different columns'; 

f1 = JOIN large BY $19,filter_file BY $0; 
f2 = JOIN large BY $20,filter_file BY $1; 
final = UNION f1,f2; 
DUMP final;