How to categorize to age ranges and find the top 3? - hadoop

Question

Having a hive table with age column consisting of age of persons.
Have to count and display the top 3 age categories.
Ex: whether below 10, 10-15, 15-20, 20-25, 25-30, ...
Which age category appears more.
Please suggest me a query to do this.

Answer 1

select case
when age <= 10 then '0-10'
else concat_ws
(
'-'
,cast(floor(age/5)*5 as string)
,cast((floor(age/5)+1)*5 as string)
)
end as age_group
,count(*) as cnt
from mytable
group by 1
order by cnt desc
limit 3
;
You might need to set this parameter:
set hive.groupby.orderby.position.alias=true;
Demo
with mytable as
(
select floor(rand()*100) as age
from (select 1) x lateral view explode(split(space(100),' ')) pe
)
select case
when age <= 10 then '0-10'
else concat_ws('-',cast(floor(age/5)*5 as string),cast((floor(age/5)+1)*5 as string))
end as age_group
,count(*) as cnt
,sort_array(collect_list(age)) as age_list
from mytable
group by 1
order by cnt desc
;
+-----------+-----+------------------------------+
| age_group | cnt | age_list |
+-----------+-----+------------------------------+
| 0-10 | 9 | [0,0,1,3,3,6,8,9,10] |
| 25-30 | 9 | [26,26,28,28,28,28,29,29,29] |
| 55-60 | 8 | [55,55,56,57,57,57,58,58] |
| 35-40 | 7 | [35,35,36,36,37,38,39] |
| 80-85 | 7 | [80,80,81,82,82,82,84] |
| 30-35 | 6 | [31,32,32,32,33,34] |
| 70-75 | 6 | [70,70,71,71,72,73] |
| 65-70 | 6 | [65,67,67,68,68,69] |
| 50-55 | 6 | [51,53,53,53,53,54] |
| 45-50 | 5 | [45,45,48,48,49] |
| 85-90 | 5 | [85,86,87,87,89] |
| 75-80 | 5 | [76,77,78,79,79] |
| 20-25 | 5 | [20,20,21,22,22] |
| 15-20 | 5 | [17,17,17,18,19] |
| 10-15 | 4 | [11,12,12,14] |
| 95-100 | 4 | [95,95,96,99] |
| 40-45 | 3 | [41,44,44] |
| 90-95 | 1 | [93] |
+-----------+-----+------------------------------+