Apache PIG中是否有条件IF运算符？ [英] Is there any Conditional IF like operator in Apache PIG?

问题描述

实际上，我正在编写PIG脚本，并希望在条件满足时执行一些语句集。

我设置了一个变量并检查某个值的变量。假设

  if flag == 0 then 
 A = LOAD'file'使用PigStorage（）as（f1：int ，...）; 
 B = ...; 
 C = ....; 
 else 
再一些Pig拉丁语句
  

我可以在PIG Script中执行此操作吗？如果是的话，那么我该如何做到这一点？

谢谢。

解决方案

是的，Pig确实提供了一个if-then-else的结构，但它没有以你问的方式使用。

猪的if-then-else 是一个算术运算符，用简写condition？true_value：false_value作为表达式的一部分进行调用，例如：

  X = FOREACH A GENERATE f2，（f2 == 1？1：COUNT（B））; 
  

您必须已经加载了表A才能执行此操作。要执行整个Pig语句的控制流程，您需要按照Fakrudeen的建议 oozie 。 p>

Actually I am writing PIG Script and want to execute some set of statements if one of the condition is satisfied.

I have set one variable and checking for some value of that variable. Suppose

if flag==0 then
  A = LOAD 'file' using PigStorage() as (f1:int, ....);
  B = ...;
  C = ....;
else 
  again some Pig Latin statements

Can I do this in PIG Script? If yes, then how can I do this?

Thanks.

解决方案

Yes, Pig does offer an if-then-else construction, but it is not used in the way you're asking.

Pig's if-then-else is an arithmetic operator invoked with the shorthand "condition ? true_value : false_value" as part of an expression, such as:

X = FOREACH A GENERATE f2, (f2==1?1:COUNT(B));

You have to already have loaded the table A to do this. To execute control flow around entire Pig statements you'll need something like oozie, as suggested by Fakrudeen.

这篇关于Apache PIG中是否有条件IF运算符？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！