COVAR_POP¶
Returns the population covariance of value pairs.
See also: COVAR_SAMP
Syntax¶
-- As an aggregate
COVAR_POP( expr1, expr2 )
-- As a window function
COVAR_POP ( expr1, expr2 ) OVER (
[ PARTITION BY value_expression [, ...] ]
[ ORDER BY value_expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] ]
[ frame_clause ]
)
Arguments¶
Parameter | Description |
---|---|
expr1 , expr2 |
Numeric expression |
Returns¶
Returns the population covariance with type DOUBLE
.
Notes¶
- When all rows contain
NULL
values, the function returnsNULL
.
Examples¶
For these examples, assume a table named nba
, with the following structure:
CREATE TABLE nba
(
"Name" varchar(40),
"Team" varchar(40),
"Number" tinyint,
"Position" varchar(2),
"Age" tinyint,
"Height" varchar(4),
"Weight" real,
"College" varchar(40),
"Salary" float
);
Here’s a peek at the table contents (Download nba.csv
):
Name | Team | Number | Position | Age | Height | Weight | College | Salary |
---|---|---|---|---|---|---|---|---|
Avery Bradley | Boston Celtics | 0.0 | PG | 25.0 | 6-2 | 180.0 | Texas | 7730337.0 |
Jae Crowder | Boston Celtics | 99.0 | SF | 25.0 | 6-6 | 235.0 | Marquette | 6796117.0 |
John Holland | Boston Celtics | 30.0 | SG | 27.0 | 6-5 | 205.0 | Boston University | |
R.J. Hunter | Boston Celtics | 28.0 | SG | 22.0 | 6-5 | 185.0 | Georgia State | 1148640.0 |
Jonas Jerebko | Boston Celtics | 8.0 | PF | 29.0 | 6-10 | 231.0 | 5000000.0 | |
Amir Johnson | Boston Celtics | 90.0 | PF | 29.0 | 6-9 | 240.0 | 12000000.0 | |
Jordan Mickey | Boston Celtics | 55.0 | PF | 21.0 | 6-8 | 235.0 | LSU | 1170960.0 |
Kelly Olynyk | Boston Celtics | 41.0 | C | 25.0 | 7-0 | 238.0 | Gonzaga | 2165160.0 |
Terry Rozier | Boston Celtics | 12.0 | PG | 22.0 | 6-2 | 190.0 | Louisville | 1824360.0 |
Simple covariance¶
t=> SELECT "Team", COVAR_POP("Age","Salary") FROM nba GROUP BY 1 ORDER BY 2 ASC;
Team | covar_pop
-----------------------+--------------
Cleveland Cavaliers | -9192828.8163
San Antonio Spurs | -6938848.9867
Oklahoma City Thunder | -3696440.1244
Detroit Pistons | -1313564.5067
Los Angeles Clippers | -968077.3778
New Orleans Pelicans | -440360.5374
Utah Jazz | 930824.7689
Philadelphia 76ers | 1458110.3265
Sacramento Kings | 2306106.08
Dallas Mavericks | 2418733.4356
Washington Wizards | 2427928.8978
Milwaukee Bucks | 2616404.8555
Orlando Magic | 2812867.8673
Golden State Warriors | 3352356.3333
Portland Trail Blazers | 3941655.4533
Denver Nuggets | 3966387.1122
Minnesota Timberwolves | 4492620.0237
Toronto Raptors | 4524417.1244
Charlotte Hornets | 5056864.8
Houston Rockets | 5309246.2089
Phoenix Suns | 5580976.6889
Indiana Pacers | 5757986.9067
Boston Celtics | 5797738.7245
Brooklyn Nets | 6119732.0667
Chicago Bulls | 6506357.92
Atlanta Hawks | 8859452.0667
Memphis Grizzlies | 9524269
New York Knicks | 10264800.6875
Miami Heat | 13009610.4734
Los Angeles Lakers | 15400203.6533