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 |
---|---|
|
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" text,
"Team" text,
"Number" tinyint,
"Position" text,
"Age" tinyint,
"Height" text,
"Weight" real,
"College" text,
"Salary" float
);
Here’s a peek at the table contents (Download nba.csv
):
Avery Bradley |
Boston Celtics |
0 |
PG |
25 |
2-Jun |
180 |
Texas |
7730337 |
---|---|---|---|---|---|---|---|---|
Jae Crowder |
Boston Celtics |
99 |
SF |
25 |
6-Jun |
235 |
Marquette |
6796117 |
John Holland |
Boston Celtics |
30 |
SG |
27 |
5-Jun |
205 |
Boston University |
|
R.J. Hunter |
Boston Celtics |
28 |
SG |
22 |
5-Jun |
185 |
Georgia State |
1148640 |
Jonas Jerebko |
Boston Celtics |
8 |
PF |
29 |
10-Jun |
231 |
5000000 |
|
Amir Johnson |
Boston Celtics |
90 |
PF |
29 |
9-Jun |
240 |
12000000 |
|
Jordan Mickey |
Boston Celtics |
55 |
PF |
21 |
8-Jun |
235 |
LSU |
1170960 |
Kelly Olynyk |
Boston Celtics |
41 |
C |
25 |
Jul-00 |
238 |
Gonzaga |
2165160 |
Terry Rozier |
Boston Celtics |
12 |
PG |
22 |
2-Jun |
190 |
Louisville |
1824360 |
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