KURT,KURT_POP,KURTOSIS
Description
The KURTOSIS function returns the kurtosis (opens in a new tab) of the expr expression.
The forumula used for this function is 4-th centrol moment / ((variance)^2) - 3.
Alias
KURT_POP,KURTOSIS
Syntax
KURTOSIS(<expr>)Parameters
| Parameters | Description |
|---|---|
<expr> | The expression needs to be obtained |
Return Value
Returns a value of type DOUBLE. Special cases:
- Returns NULL when the variance is zero.
Example
select * from statistic_test;+-----+------+------+
| tag | val1 | val2 |
+-----+------+------+
| 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) |
+-------------------+--------------------+
| 0.162124583734851 | -1.3330994719286338 |
+-------------------+--------------------+// Each group just has one row, result is NULL
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 |
+------------+------------+