Categories:: Aggregate functions (Linear Regression) , Window functions

REGR_AVGX¶

Returns the average of the independent variable for non-null pairs in a group, where x is the independent variable and y is the dependent variable.

Syntax¶

Aggregate function

REGR_AVGX(y, x)

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Window function

REGR_AVGX(y, x) OVER ( [ PARTITION BY <expr3> ] )

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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.

Usage notes¶

DISTINCT is not supported for this function.
In order for a row to be included in the average, BOTH the x and y values must be non-NULL.

When this function is called as a window function, it does not support:
- An ORDER BY clause within the OVER clause.
- Explicit 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);

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SELECT k, REGR_AVGX(v, v2) FROM aggr GROUP BY k;

---+------------------+
 k | regr_avgx(v, v2) |
---+------------------+
 1 | [NULL]           |
 2 | 22.666666667     |
---+------------------+

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