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Function Argument Type Return Type Description=== Sample call of an aggregate function ===corr(Y, X) double precision double precision correlation coefficientcovar_pop SELECT regr_slope(Ytothullcount, Xavghullcount) double precision double precision population covarianceFROM hcllayerwinv;covar_samp(Y, X) double precision double precision sample covarianceregr_avgx(Y, X) double precision double precision average of the independent variable (sum(X)/N)==== Output ====regr_avgy(Y, X) double precision double precision average of the dependent variable (sum(Y)/N) regr_slope regr_count(Y, X) double precision bigint number of input rows in which both expressions are nonnullregr_intercept(Y, X) double precision double precision y -------intercept of the least-squares-fit linear equation determined by the (X, Y) pairsregr_r2(Y, X) double precision double precision square of the correlation coefficientregr_slope(Y, X) double precision double precision slope of the least-squares-fit linear equation determined by the (X, Y) pairsregr_sxx(Y, X) double precision double precision sum(X^2) - sum(X)^2/N ("sum of squares" of the independent variable)regr_sxy(Y, X) double precision double precision sum(X*Y) - sum(X) * sum(Y)/N ("sum of products" of independent times dependent variable)regr_syy(Y, X) double precision double precision sum(Y^2) - sum(Y)^2/N ("sum of squares" of the dependent variable)stddev(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric historical alias for stddev_sampstddev_pop(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric population standard deviation of the input valuesstddev_samp(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric sample standard deviation of the input valuesvariance(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric historical alias for var_sampvar_pop(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric population variance of the input values (square of the population standard deviation) 2.31850202053387var_samp(expression) smallint, int, bigint, real, double precision, or numeric double precision for floating-point arguments, otherwise numeric sample variance of the input values (square of the sample standard deviation1 row)
→Sample call of an aggregate function
Table 9-44. Aggregate Functions for Statistics
Function | Argument Type | Return Type | Description
=======================+==========================================================+=================================================================+=============================================================================================
corr(Y, X) | double precision | double precision | correlation coefficient
covar_pop(Y, X) | double precision | double precision | population covariance
covar_samp(Y, X) | double precision | double precision | sample covariance
regr_avgx(Y, X) | double precision | double precision | average of the independent variable (sum(X)/N)
regr_avgy(Y, X) | double precision | double precision | average of the dependent variable (sum(Y)/N)
regr_count(Y, X) | double precision | bigint | number of input rows in which both expressions are nonnull
regr_intercept(Y, X) | double precision | double precision | y-intercept of the least-squares-fit linear equation determined by the (X, Y) pairs
regr_r2(Y, X) | double precision | double precision | square of the correlation coefficient
regr_slope(Y, X) | double precision | double precision | slope of the least-squares-fit linear equation determined by the (X, Y) pairs
regr_sxx(Y, X) | double precision | double precision | sum(X^2) - sum(X)^2/N ("sum of squares" of the independent variable)
regr_sxy(Y, X) | double precision | double precision | sum(X*Y) - sum(X) * sum(Y)/N ("sum of products" of independent times dependent variable)
regr_syy(Y, X) | double precision | double precision |sum(Y^2) - sum(Y)^2/N ("sum of squares" of the dependent variable)
stddev(expression) | smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| historical alias for stddev_samp
stddev_pop(expression) | smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| population standard deviation of the input values
stddev_samp(expression)| smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| sample standard deviation of the input values
variance(expression) | smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| historical alias for var_samp
var_pop(expression) | smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| population variance of the input values (square of the population standard deviation)
var_samp(expression) | smallint, int, bigint, real, double precision, or numeric| double precision for floating-point arguments, otherwise numeric| sample variance of the input values (square of the sample standard deviation)
==Joe Conway's Documentation on pl/r==
3
(1 row)
=== Attempts to call R built-in function from PSQL ===
==== Regression ====
Creating Function:
CREATE OR REPLACE FUNCTION r_reg(y numeric[], x numeric[])
RETURNS numeric AS $$
res <- lm(y ~ x)
return(coef(res)[1])
$$ LANGUAGE 'plr' immutable;
Calling Function:
SELECT r_reg(tothullcount, avghullcount) from hcllayerwinv;
Results:
r_reg
-------
0
0
3
0
5
4
0
0
5
4
0
0
6
4
4
0
0
4
0
0
4
0
0
4
0
0
3
0
5
3
0
0
7
5
3
3
0
0
6
4
0
0
0
5
4
0
0
7
== hcllayerwinv table from tigertest database ==
