motiejus/stud
1
Fork 0
Code Releases Activity

move first semester to first semester

Browse Source
This commit is contained in:
Motiejus Jakštys
2020-04-08 22:49:30 +03:00
parent db18a17f66
commit b97b04e9bb
93 changed files with 0 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
I/MTM/task4-straipsnis/.gitignore vendored Normal file
View File

@@ -0,0 +1,2 @@
/db/
/README.html

8
I/MTM/task4-straipsnis/Makefile Normal file
View File

@@ -0,0 +1,8 @@
toolshed = docker run --rm -v $(PWD):/x -w /x motiejus/toolshed
all: README.html
README.html: README.md
$(toolshed) pandoc \
-T "$(shell head -1 $<)" \
--self-contained $< -o $@

274
I/MTM/task4-straipsnis/README.md Normal file
View File

@@ -0,0 +1,274 @@
Pasaulio oro uostų įdomybės
===========================
Kai mokėmės duomenų bazių, paprastai pavyzdiniai duomenų bazių modeliai būdavo
gana panašūs vienas į kitą ir nuobodūs: sumodeliuoti biblioteką, sumodeliuoti
"draugų" duomenų bazę, ar gyvūnų klasifikaciją.
Šis įrašas parodys, kaip prie nuobodžių SQL tipų greitai galima pridėti
erdvinius, ir iš karto kokius įdomius klausimus galime uždavinėti. Apie oro
uostus. :)
Duomenų bazės sukūrimas
-----------------------
Susikurkime PostgreSQL lentelę su viso pasaulio oro uostais (bent tais, kurie
turi [IATA kodą][1]). Oro uostų informaciją gausime iš [openflights.org][3].
```
$ ./managedb init
```
Visi skriptai ir `airports.dat` (oro uostų informacija) yra [šioje
repositorijoje][2]; skriptai nedideli. Kad suprastumėte toliau esančias SQL
užklausas, rekomenduoju perskaityti `init.sql`.
Kai duombazė sukurta ir duomenys importuoti, patikrinkime, kas viduje:
```
psql airportgames <<<"
SELECT
iata,
name,
to_char(st_y (geom), '999.99') AS latitude,
to_char(st_x (geom), '999.99') AS longitude,
to_char(st_z (geom), '9999') AS altitude
FROM
airports
WHERE
iata IN ('VNO', 'RIX', 'TLL');
"
iata | name | latitude | longitude | altitude
------+-------------------------------+----------+-----------+----------
TLL | Lennart Meri Tallinn Airport | 59.41 | 24.83 | 40
RIX | Riga International Airport | 56.92 | 23.97 | 11
VNO | Vilnius International Airport | 54.63 | 25.29 | 198
```
Matome Vilniaus, Rygos ir Talino oro uostų informaciją: IATA kodą, pavadinimą,
ilgumą, platumą, aukštį virš jūros lygio metrais.
Dabar, kai informacija ranka pasiekiama, užduokime kelis įdomesnius klausimus,
ir juos atsakykime.
Užklausos
---------
**Kokie oro uostai yra labiausiai nutolę vienas nuo kito?**
```
SELECT
a.country AS a_country,
a.iata AS a_iata,
b.country AS b_country,
b.iata AS b_iata,
to_char(st_distance (a.geom, b.geom, TRUE) / 1000, '99999.99') AS distance_km
FROM
airports a,
airports b
WHERE
a.iata != '\N'
AND b.iata != '\N'
AND a.gid > b.gid
ORDER BY
distance_km DESC
LIMIT 10;
a_country | a_iata | b_country | b_iata | distance_km
------------------+--------+-------------------------+--------+-------------
China | ZQZ | Argentina | OES | 20002.42
Saudi Arabia | KMX | French Polynesia | PUK | 20000.78
Indonesia | TKG | Colombia | MQU | 20000.53
French Polynesia | NAU | Ethiopia | AXU | 20000.47
Nicaragua | RNI | Cocos (Keeling) Islands | CCK | 20000.20
China | JGS | Argentina | TUC | 19999.93
Malaysia | LGL | Brazil | TFF | 19998.43
New Zealand | HLZ | Spain | ODB | 19998.36
Indonesia | PLM | Colombia | NVA | 19998.19
Malaysia | KBR | Peru | CHH | 19998.13
```
Turint galvoje, kad pusė atstumo aplink žemę ties ekvatoriais yra 20037.50 km
(ties poliais - 20004 km!), atstumas tarp tolimiausių oro uostų yra gana arti
teorinio maksimumo: trūksta tik 35km iki teorinio maksimumo ties ekvatoriumi,
ir tik 2km iki teorinio maksimumo ties poliais.
**Kurie oro uostai yra arčiausiai vienas kito?**
```
SELECT
a.country AS a_country,
a.iata AS a_iata,
b.country AS b_country,
b.iata AS b_iata,
to_char(st_y (a.geom), 'FMSG999.0000') || ',' || to_char(st_x (a.geom), 'FMSG999.0000') AS a_latlng,
to_char(st_y (b.geom), 'FMSG999.0000') || ',' || to_char(st_x (b.geom), 'FMSG999.0000') AS b_latlng,
to_char(st_distance (a.geom, b.geom, TRUE) / 1000, '99999.99') AS distance_km
FROM
airports a,
airports b
WHERE
a.iata != '\N'
AND b.iata != '\N'
AND a.gid > b.gid
ORDER BY
a.geom <-> b.geom ASC
LIMIT 10;
a_country | a_iata | b_country | b_iata | a_latlng | b_latlng | distance_km
------------------+--------+------------------+--------+--------------------+--------------------+-------------
Australia | JHQ | Australia | WSY | -20.2772,+148.7556 | -20.2761,+148.7550 | 0.14
Papua New Guinea | NDN | Papua New Guinea | KGW | -9.1436,+147.6842 | -9.1359,+147.6694 | 1.83
Papua New Guinea | KGW | Papua New Guinea | EFG | -9.1359,+147.6694 | -9.1538,+147.6598 | 2.24
Rwanda | GYI | Congo (Kinshasa) | GOM | -1.6772,+29.2589 | -1.6708,+29.2385 | 2.38
Papua New Guinea | NDN | Papua New Guinea | EFG | -9.1436,+147.6842 | -9.1538,+147.6598 | 2.92
Papua New Guinea | BNM | Papua New Guinea | KGW | -9.1078,+147.6667 | -9.1359,+147.6694 | 3.13
Virgin Islands | SPB | Virgin Islands | STT | +18.3386,-64.9407 | +18.3373,-64.9734 | 3.46
United States | SDM | Mexico | TIJ | +32.5723,-116.9800 | +32.5411,-116.9700 | 3.59
French Guiana | LDX | Suriname | ABN | +5.4831,-54.0344 | +5.5127,-54.0501 | 3.71
Papua New Guinea | BNM | Papua New Guinea | NDN | -9.1078,+147.6667 | -9.1436,+147.6842 | 4.40
```
140 metrų atstumu esantys JHQ ir WSY oro uostai Australijoje atrodo kaip [tas
pats objektas][10]. `NDN` ir `KGW` atrodo kaip du [nupjautos žolės
ruožai, skirti nusileisti lėktuvams][4], užskaitysime! Ketvirtosios vietos
laimėtojus tarp Ruandos ir Kongo [skiria 2.38 km][8], ir tai jau tikri nemaži
oro uostai.
**Aukščiausiai virš jūros lygio esantys oro uostai?**
```
SELECT
iata,
name,
country,
to_char(st_z (geom), '9999') AS altitude_m
FROM
airports
ORDER BY
altitude_m DESC
LIMIT 10;
iata | name | country | altitude_m
------+----------------------------------------+---------+------------
DCY | Daocheng Yading Airport | China | 4411
BPX | Qamdo Bangda Airport | China | 4334
KGT | Kangding Airport | China | 4280
NGQ | Ngari Gunsa Airport | China | 4274
LPB | El Alto International Airport | Bolivia | 4071
POI | Capitan Nicolas Rojas Airport | Bolivia | 3936
YUS | Yushu Batang Airport | China | 3906
\N | Copacabana Airport | Bolivia | 3838
JUL | Inca Manco Capac International Airport | Peru | 3826
GMQ | Golog Maqin Airport | China | 3787
```
**Žemiausiai po jūros lygiu esantys oro uostai?**
```
SELECT
iata,
name,
country,
to_char(st_z (geom), 'FMSG999.00') AS altitude_m
FROM
airports
WHERE
iata != '\N'
ORDER BY
st_z (geom) ASC
LIMIT 10;
iata | name | country | altitude_m
------+--------------------------------------+---------------+------------
MTZ | Bar Yehuda Airfield | Israel | -385.88
EIY | Ein Yahav Airfield | Israel | -49.99
TRM | Jacqueline Cochran Regional Airport | United States | -35.05
GUW | Atyrau Airport | Kazakhstan | -21.95
RZR | Ramsar Airport | Iran | -21.34
ASF | Astrakhan Airport | Russia | -19.81
NSH | Noshahr Airport | Iran | -18.59
IPL | Imperial County Airport | United States | -16.46
NJK | El Centro NAF Airport (Vraciu Field) | United States | -12.80
RAS | Sardar-e-Jangal Airport | Iran | -12.19
```
Aukštai ir žemai esantiems oro uostams turbūt komentarų daug nereikia. Tiesa,
abejose kategorijose turime aiškias šalis-lyderes.
**Arčiausiai ašigalių esantys oro uostai?**
Čia nusižengsime iki šiol buvusiai taisyklei filtruoti oro uostus tik su IATA kodais. Jūsų malonumui:
```
SELECT
name,
country,
to_char(st_y (geom), 'FMSG999.0000') || ',' || to_char(st_x (geom), 'FMSG999.0000') AS a_latlng
FROM
airports
WHERE
gid != 13011
ORDER BY
abs(st_y (geom)) DESC
LIMIT 15;
name | country | a_latlng
----------------------------------+------------+--------------------
South Pole Station Airport | Antarctica | -90.0000,+.0000
Alert Airport | Canada | +82.5178,-62.2806
Nagurskoye | Russia | +80.8032,+47.6636
Eureka Airport | Canada | +79.9947,-85.8142
Ny-Ålesund Airport (Hamnerabben) | Svalbard | +78.9275,+11.8743
Pyramiden Heliport | Norway | +78.6523,+16.3372
Svalbard Airport, Longyear | Norway | +78.2461,+15.4656
McMurdo Station Pegasus Field | Antarctica | -77.9634,+166.5250
Svea Airport | Svalbard | +77.8969,+16.7250
Williams Field | Antarctica | -77.8674,+167.0570
McMurdo Station Ice Runway | Antarctica | -77.8540,+166.4690
Siorapaluk Heliport | Greenland | +77.7865,-70.6387
Qaanaaq Airport | Greenland | +77.4886,-69.3887
Thule Air Base | Greenland | +76.5312,-68.7032
Grise Fiord Airport | Canada | +76.4261,-82.9092
```
**Atstumas tarp šiauriausio ir piečiausio oro uosto?**
```
SELECT
to_char(
st_distance (
(SELECT geom FROM airports WHERE name = 'South Pole Station Airport'),
(SELECT geom FROM airports WHERE name = 'Alert Airport'),
TRUE
)/1000,
'99999.99') AS km;
km
-----------
19168.26
```
Pabaigai
--------
PostGis prie pažįstamos ir galingos PostgreSQL sąsajos suteikia erdvines
[funkcijas, duomenų tipus ir indeksavimo galimybes][9]. Jau žinant PostgreSQL,
importuoti erdvinius duomenis ir pradėti juos analizuoti reikia tikrai ne daug.
Užduotys susidomėjusiam skaitytojui:
* Kodėl artimiausių oro uostų užklausoje naudojome [<->][5], o
tolimiausių -- [`st_distance`][6]?
* Kokį atstumą skristume aplink žemę Vilniaus platuma?
* Kiek kartų reikia nuskristi United Economy klase aplink žemę Vilniaus
platuma, kad uždirbtume [nemokamus pusryčius][7]?
[1]: https://en.wikipedia.org/wiki/International_Air_Transport_Association_code
[2]: https://github.com/motiejus/stud/tree/master/MTM/task4-straipsnis
[3]: https://openflights.org/data.html
[4]: https://goo.gl/maps/RD3d9fsH8NwzAnsYA
[5]: https://postgis.net/docs/geometry_distance_knn.html
[6]: https://postgis.net/docs/ST_Distance.html
[7]: https://www.united.com/ual/en/us/fly/mileageplus/premier/full-premier-benefits-chart.html
[8]: https://goo.gl/maps/3usBcUHDWnefVmab6
[9]: https://postgis.net/docs/reference.html
[10]: https://goo.gl/maps/T6WQhT2FDUdymnRB9

7698
I/MTM/task4-straipsnis/airports.dat Normal file
View File

File diff suppressed because it is too large Load Diff

36
I/MTM/task4-straipsnis/init.sql Normal file
View File

@@ -0,0 +1,36 @@
-- schema
CREATE TABLE airports (
gid SERIAL NOT NULL PRIMARY KEY,
name TEXT,
city TEXT,
country TEXT,
iata TEXT,
icao TEXT,
geom GEOMETRY,
latitude DOUBLE PRECISION,
longitude DOUBLE PRECISION,
altitude DOUBLE PRECISION,
timezone TEXT,
dst TEXT,
tz TEXT,
type TEXT,
source TEXT,
CONSTRAINT enforce_dims_geom CHECK (st_ndims(geom) = 3),
CONSTRAINT enforce_geotype_geom CHECK (geometrytype(geom) = 'POINT'::text OR geom IS NULL),
CONSTRAINT enforce_srid_geom CHECK (st_srid(geom) = 4326)
);
-- create index for faster spatial lookups
CREATE INDEX idx_geom ON airports USING GIN (geom);
-- import data from airports.dat
\copy airports(gid, name, city, country, iata, icao, latitude, longitude, altitude, timezone, dst, tz, type, source) FROM 'airports.dat' DELIMITERS ',' CSV;
-- put lat/lon/altitude to the "real" geom field
UPDATE airports
SET geom = ST_SetSRID(ST_MakePoint(longitude, latitude, altitude * 0.3048),4326);
ALTER TABLE airports DROP COLUMN latitude;
ALTER TABLE airports DROP COLUMN longitude;
ALTER TABLE airports DROP COLUMN altitude;
ALTER TABLE airports DROP COLUMN type;
ALTER TABLE airports DROP COLUMN source;

22
I/MTM/task4-straipsnis/managedb Executable file
View File

@@ -0,0 +1,22 @@
#!/bin/bash
set -xeuo pipefail
if [[ $1 == init ]]; then
mkdir -p db && initdb db
pg_ctl -D db -l db/logfile start
psql postgres \
-c 'CREATE DATABASE airportgames;'
psql -d airportgames \
-c 'CREATE EXTENSION postgis;'
psql -d airportgames < init.sql
fi
if [[ $1 == start ]]; then
pg_ctl -D db -l db/logfile start
fi
if [[ $1 == stop ]]; then
pg_ctl -D db -l db/logfile stop
fi