- Categories:
Aggregate Functions (Linear Regression) , Window Functions
REGR_SLOPE¶
Returns the slope of the linear regression line for non-null pairs in a group. It is computed for non-null pairs using the following formula:
COVAR_POP(x,y) / VAR_POP(x)
Where x
is the independent variable and y
is the dependent variable.
Syntax¶
Aggregate function
REGR_SLOPE(y, x)
Window function
REGR_SLOPE(y, x) OVER ( [ PARTITION BY <expr3> ] )
Arguments¶
y
The dependent variable. This must be an expression that can be evaluated to a numeric type.
x
The independent variable. This must be an expression that can be evaluated to a numeric type.
expr3
This is the optional expression used to group rows into partitions.
Important
Note the order of the arguments; the dependent variable is first.
Returns¶
The data type of the returned value is FLOAT.
Usage Notes¶
DISTINCT is not supported for this function.
When used as a window function:
This function does not support:
ORDER BY sub-clause in the OVER() clause.
Window frames.
Examples¶
create or replace table aggr(k int, v decimal(10,2), v2 decimal(10, 2));
insert into aggr values(1, 10, null);
insert into aggr values(2, 10, 11), (2, 20, 22), (2, 25,null), (2, 30, 35);
select k, regr_slope(v, v2) from aggr group by k;
---+-------------------+
k | regr_slope(v, v2) |
---+-------------------+
1 | [NULL] |
2 | 0.831408776 |
---+-------------------+