REGR_R2() GROUP BY ...

All functions > GROUP BY > REGR_R2() GROUP BY ...

Returns the coefficient of determination (R²) of the linear regression.

Syntax

REGR_R2(expr_y, expr_x)
 [ FILTER (WHERE condition) ]
  [ GROUP BY feature [, feature ...] ]

REGR_R2(expr_y, expr_x)
 [ FILTER (WHERE condition) ]
  [ GROUP BY feature [, feature ...] ]

Notes

• Equivalent to POWER(CORR(y, x), 2)
• Returns a value between 0 (no fit) and 1 (perfect fit)
• NULL values in either expression are excluded from the calculation
• Returns NULL if fewer than 2 non-NULL pairs exist

Examples

SELECT
    -- Coefficient of determination for a perfect linear fit
    f1 := ZIP(ARRAY(1, 2, 3) AS x, ARRAY(2, 4, 6) AS y).TRANSFORM(
        SELECT REGR_R2(y, x)
    ).UNWRAP_ONE()
;