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* Group by a range of values
@ 2020-08-01 12:14 Mike Martin <redtux1@gmail.com>
0 siblings, 2 replies; 5+ messages in thread
From: Mike Martin @ 2020-08-01 12:14 UTC (permalink / raw)
To: pgsql-sql <pgsql-sql@lists.postgresql.org>
Say I have a field of ints, as for example created by with ordinality or
generate_series, is it possible to group by a range? eq
1,2,3,4,5,6,7,8,9,10
step 3
so output is
1 1
2 1
3 1
4 2
5 2
6 2
7 3
8 3
9 3
10 4
thanks
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Group by a range of values
@ 2020-08-01 12:34 Torsten Grust <torsten.grust@gmail.com>
parent: Mike Martin <redtux1@gmail.com>
1 sibling, 2 replies; 5+ messages in thread
From: Torsten Grust @ 2020-08-01 12:34 UTC (permalink / raw)
To: pgsql-sql <pgsql-sql@lists.postgresql.org>
Hi,
maybe this does the job already (/ is integer division):
SELECT i, 1 + (i-1) / 3
FROM generate_series(1,10) AS i;
An expression like (i-1) / 3 could, of course, also be used as partitioning
criterion in GROUP BY and/or window functions.
Cheers,
—T
On Sat, Aug 1, 2020 at 2:15 PM Mike Martin <redtux1@gmail.com> wrote:
> Say I have a field of ints, as for example created by with ordinality or
> generate_series, is it possible to group by a range? eq
>
> 1,2,3,4,5,6,7,8,9,10
> step 3
> so output is
>
> 1 1
> 2 1
> 3 1
> 4 2
> 5 2
> 6 2
> 7 3
> 8 3
> 9 3
> 10 4
>
> thanks
>
--
| Torsten Grust
| Torsten.Grust@gmail.com
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Group by a range of values
@ 2020-08-01 12:53 Rob Sargent <robjsargent@gmail.com>
parent: Torsten Grust <torsten.grust@gmail.com>
1 sibling, 0 replies; 5+ messages in thread
From: Rob Sargent @ 2020-08-01 12:53 UTC (permalink / raw)
To: pgsql-sql@lists.postgresql.org
On 8/1/20 6:34 AM, Torsten Grust wrote:
> Hi,
>
> maybe this does the job already (/ is integer division):
>
> SELECT i, 1 + (i-1) / 3
> FROM generate_series(1,10) AS i;
>
> An expression like (i-1) / 3 could, of course, also be used as
> partitioning criterion in GROUP BY and/or window functions.
>
> Cheers,
> —T
>
> On Sat, Aug 1, 2020 at 2:15 PM Mike Martin <redtux1@gmail.com
> <mailto:redtux1@gmail.com>> wrote:
>
> Say I have a field of ints, as for example created by with
> ordinality or generate_series, is it possible to group by a range? eq
>
> 1,2,3,4,5,6,7,8,9,10
> step 3
> so output is
>
> 1 1
> 2 1
> 3 1
> 4 2
> 5 2
> 6 2
> 7 3
> 8 3
> 9 3
> 10 4
>
> thanks
>
>
>
> --
> | Torsten Grust
> | Torsten.Grust@gmail.com <mailto:Torsten.Grust@gmail.com>
>
My version is as follows, the point being that the "grouping" requested
is simply an ordering of the step mechanism. Naturally this series is
generated in order shown but real data for val likely won't be.
test=# with ts as (select generate_series(1,10) as val) select s.val,
(s.val /3)+1 as ord from ts as s order by ord;
val | ord
-----+-----
1 | 1
2 | 1
3 | 2
4 | 2
5 | 2
6 | 3
7 | 3
8 | 3
9 | 4
10 | 4
(10 rows)
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Group by a range of values
@ 2020-08-01 18:55 Steve Midgley <science@misuse.org>
parent: Mike Martin <redtux1@gmail.com>
1 sibling, 0 replies; 5+ messages in thread
From: Steve Midgley @ 2020-08-01 18:55 UTC (permalink / raw)
To: Mike Martin <redtux1@gmail.com>; +Cc: pgsql-sql <pgsql-sql@lists.postgresql.org>
On Sat, Aug 1, 2020 at 5:15 AM Mike Martin <redtux1@gmail.com> wrote:
> Say I have a field of ints, as for example created by with ordinality or
> generate_series, is it possible to group by a range? eq
>
> 1,2,3,4,5,6,7,8,9,10
> step 3
> so output is
>
> 1 1
> 2 1
> 3 1
> 4 2
> 5 2
> 6 2
> 7 3
> 8 3
> 9 3
> 10 4
>
> thanks
>
*My solution would be:*
select num, ceiling(CAST (num as float)/3) as grp from Agg
*Yields:*
num grp
1 1
2 1
3 1
4 2
5 2
6 2
7 3
8 3
9 3
10 4
*For DDL of: *
CREATE TABLE Agg
("num" int);
INSERT INTO Agg
("num")
VALUES
(1),
(2),
(3),
(4),
(5),
(6),
(7),
(8),
(9),
(10);
I created this in SQL Fiddle: http://sqlfiddle.com/#!17/37519e/30/0
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Group by a range of values
@ 2020-08-08 11:29 Samed YILDIRIM <samed@reddoc.net>
parent: Torsten Grust <torsten.grust@gmail.com>
1 sibling, 0 replies; 5+ messages in thread
From: Samed YILDIRIM @ 2020-08-08 11:29 UTC (permalink / raw)
To: Torsten Grust <torsten.grust@gmail.com>; pgsql-sql <pgsql-sql@lists.postgresql.org>
<div><div>Hi,</div><div> </div><div>Another (and less optimised :)) alternative;</div><div> </div><div><div>pgsql-sql=# select m,dense_rank() over (order by (m-1)/3) from generate_series(1,10) m;</div><div>m | dense_rank</div><div>----+------------</div><div>1 | 1</div><div>2 | 1</div><div>3 | 1</div><div>4 | 2</div><div>5 | 2</div><div>6 | 2</div><div>7 | 3</div><div>8 | 3</div><div>9 | 3</div><div>10 | 4</div><div>(10 rows)</div><div> </div></div></div><div>Best regards.</div><div>Samed YILDIRIM</div><div> </div><div> </div><div> </div><div>01.08.2020, 15:35, "Torsten Grust" <torsten.grust@gmail.com>:</div><blockquote><div><div style="font-family:'arial' , sans-serif"><div style="font-family:'arial' , sans-serif">Hi,</div><div style="font-family:'arial' , sans-serif"> </div><div style="font-family:'arial' , sans-serif">maybe this does the job already (/ is integer division):</div><div style="font-family:'arial' , sans-serif"> </div><div style="font-family:'arial' , sans-serif">SELECT i, 1 + (i-1) / 3 </div><div style="font-family:'arial' , sans-serif">FROM generate_series(1,10) AS i;</div><div style="font-family:'arial' , sans-serif"> </div><div style="font-family:'arial' , sans-serif">An expression like (i-1) / 3 could, of course, also be used as partitioning criterion in GROUP BY and/or window functions.</div><div style="font-family:'arial' , sans-serif"> </div><div style="font-family:'arial' , sans-serif">Cheers,</div><div style="font-family:'arial' , sans-serif"> —T</div></div></div> <div><div>On Sat, Aug 1, 2020 at 2:15 PM Mike Martin <<a href="mailto:redtux1@gmail.com">redtux1@gmail.com</a>> wrote:</div><blockquote style="border-left-color:rgb( 204 , 204 , 204 );border-left-style:solid;border-left-width:1px;margin:0px 0px 0px 0.8ex;padding-left:1ex"><div><div>Say I have a field of ints, as for example created by with ordinality or generate_series, is it possible to group by a range? eq</div><div> </div><div>1,2,3,4,5,6,7,8,9,10</div><div>step 3</div><div>so output is</div><div> </div><div>1 1</div><div>2 1</div><div>3 1</div><div>4 2</div><div>5 2</div><div>6 2</div><div>7 3</div><div>8 3</div><div>9 3</div><div>10 4</div><div> </div><div>thanks</div></div></blockquote></div> <div> </div>--<div><div><div><div><div><font face="monospace, monospace">| Torsten Grust<br />| <a href="mailto:Torsten.Grust@gmail.com">Torsten.Grust@gmail.com</a></font><br /> </div></div></div></div></div></blockquote>
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Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2020-08-01 12:14 Group by a range of values Mike Martin <redtux1@gmail.com>
2020-08-01 12:34 ` Torsten Grust <torsten.grust@gmail.com>
2020-08-01 12:53 ` Rob Sargent <robjsargent@gmail.com>
2020-08-08 11:29 ` Samed YILDIRIM <samed@reddoc.net>
2020-08-01 18:55 ` Steve Midgley <science@misuse.org>
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