用hive实现股票的波峰和波谷

首先按照股票的代码分类，以时间排序

 create table t2 as 
  select 
  code,time,price,row_number() over(partition by code order by time) rn 
  from t1; 

最后通过case when then else end 求出波峰和波谷

 select a.code,a.time,a.price,
 case when b.price is null then "未知"
      when c.price is null then "未知"
      when a.price>b.price and a.price>c.price then "波峰"
      when a.price<b.price and a.price<c.price then "波谷"
 else "中间" end as mark,a.rn
 from t2 a 
 left join 
 t2 b on a.code=b.code and b.rn=a.rn-1
 left join
 t2 c on a.code=c.code and c.rn=a.rn+1 
order by a.code,a.rn;