KURT,KURT_POP,KURTOSIS

Description

The KURTOSIS function calculates the kurtosis of the data. The formula used is: fourth central moment / (variance squared) - 3.

Alias

KURT_POP, KURTOSIS

Syntax

KURTOSIS(<expr>)
KURT_POP(<expr>)
KURT(<expr>)

Parameters

Parameter	Description
<expr>	The expression to calculate, type Double supported.

Return Value

Returns a DOUBLE value. Returns NULL when variance is zero. Returns NULL when there is no valid data in the group.

Example

-- setup
create table statistic_test(
    tag int,
    val1 double,
    val2 double
) distributed by hash(tag) buckets 1
properties ("replication_num"="1");
insert into statistic_test values
    (1, -10, -10),
    (2, -20, null),
    (3, 100, null),
    (4, 100, null),
    (5, 1000, 1000);

select kurt(val1), kurt(val2) from statistic_test;

+---------------------+------------+
| kurt(val1)          | kurt(val2) |
+---------------------+------------+
| 0.16212458373485106 |         -2 |
+---------------------+------------+

select kurt(val1), kurt(val2) from statistic_test group by tag;

+------------+------------+
| kurt(val1) | kurt(val2) |
+------------+------------+
|       NULL |       NULL |
|       NULL |       NULL |
|       NULL |       NULL |
|       NULL |       NULL |
|       NULL |       NULL |
+------------+------------+