python/sympy_cheat/logarithm_integral.py Updated 2025-07-16
SQLite C extension Updated 2025-07-16
Example: sqlite/ip.c, adapted from www.sqlite.org/loadext.html, also mentioned explained at: stackoverflow.com/questions/7638238/sqlite-ip-address-storage/76520885#76520885.
Sample usage in the test program: sqlite/test.sh.
SQLite benchmark Updated 2025-07-16
Nested set model in SQL Updated 2025-07-16
How to implement Nested set model in SQL:
- stackoverflow.com/questions/192220/what-is-the-most-efficient-elegant-way-to-parse-a-flat-table-into-a-tree/42781302#42781302 contains the correct left/size representation and update queries, which makes it much easier to maintain the tree without having to worry about the sizes of siblings which are constant
- stackoverflow.com/questions/192220/what-is-the-most-efficient-elegant-way-to-parse-a-flat-table-into-a-tree/194031#194031 amazing ASCII art representations of the structure. Unfortunately uses a wonky left/right representation, rather than the much more natural left/size representation from the other post
Common Table Expression Updated 2025-07-16
Similar to SQL subquery, but with some differences: stackoverflow.com/questions/706972/difference-between-cte-and-subquery
rm -f tmp.sqlite
sqlite3 tmp.sqlite 'create table t(i integer)'
sqlite3 tmp.sqlite 'insert into t values (1), (2)'
sqlite3 tmp.sqlite 'with mycte as ( select * from t ) delete from mycte where i = 1'
sqlite3 tmp.sqlite 'select * from t' SQL PROCEDURE Updated 2025-07-16
SQL FUNCTION keyword Updated 2025-07-16
PostgreSQL spatial index Updated 2025-07-16
SQL
genenerate_series Updated 2025-07-16 SQL 2D histogram Updated 2025-07-16
Let's try it on SQLite 3.40.1, Ubuntu 23.04. Data setup:
sqlite3 tmp.sqlite 'create table t(x integer, y integer)'
sqlite3 tmp.sqlite <<EOF
insert into t values
(0, 0),
(1, 1),
(2, 2),
(3, 3),
(4, 4),
(5, 5),
(6, 6),
(7, 7),
(8, 8),
(9, 9),
(10, 10),
(11, 11),
(12, 12),
(13, 13),
(14, 14),
(15, 15),
(16, 16),
(17, 17),
(18, 18),
(19, 19),
(2, 18)
EOF
sqlite3 tmp.sqlite 'create index txy on t(x, y)'For a bin size of 5 ignoring empty ranges we can:which produces the desired:
sqlite3 tmp.sqlite <<EOF
select
floor(x/5)*5 as x,
floor(y/5)*5 as y,
count(*) as cnt
from t
group by 1, 2
order by 1, 2
EOF0|0|5
0|15|1
5|5|5
10|10|5
15|15|5And to consider empty ranges we can use SQL which outputs the desired:
genenerate_series + as per stackoverflow.com/questions/72367652/populating-empty-bins-in-a-histogram-generated-using-sql:sqlite3 tmp.sqlite <<EOF
select x, y, sum(cnt) from (
select
floor(x/5)*5 as x,
floor(y/5)*5 as y,
count(*) as cnt
from t
group by 1, 2
union
select *, 0 as cnt from generate_series(0, 15, 5) inner join (select * from generate_series(0, 15, 5))
)
group by x, y
EOF0|0|5
0|5|0
0|10|0
0|15|1
5|0|0
5|5|5
5|10|0
5|15|0
10|0|0
10|5|0
10|10|5
10|15|0
15|0|0
15|5|0
15|10|0
15|15|5 Python
__getitem__ Updated 2025-07-16 python/typing_cheat/protocol_empty.py Updated 2025-07-16
python/typing_cheat/protocol.py Updated 2025-07-16
Which two persons are hard to satisfy? Updated 2025-07-16
tipitaka.fandom.com/wiki/Puggala-Pannatti-Chap.2:
He who stores up whatever he gets and he who gives away whatever he gets - these two persons are hard to satisfy.
Division of human types by two Updated 2025-07-16
Bundle assets into a single file in Phaser Updated 2025-07-16
Phaser hello world Updated 2025-07-16
- phaser/hello.html: a minimal hello world adapted from web.archive.org/web/20230323212804/https://phaser.io/tutorials/getting-started-phaser3/part5. Not an actual game strictly speaking though, just shows the phaser logo bouncing around the screen.
- phaser/hello-game.html: an actually hello world game where you have to collect stars and avoid bombs.Based on labs.phaser.io/index.html?dir=games/firstgame/&q=:
- finished version: labs.phaser.io/view.html?src=src/games/firstgame/part10.js
- corresponding tutorial: web.archive.org/web/20230323210501/https://phaser.io/tutorials/making-your-first-phaser-3-game/part10.
Tab (Oxford slang) Updated 2025-07-16
University of Cambridge students, CanTabBridgeans.
Battel Updated 2025-07-16
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