owl-map/notes

# vim: spell:tw=80 ft=markdown

Extracted items from data dump that include "P625" with the quotes. There are 8,398,490 matching items.

Nearest-Neighbour Searching

https://postgis.net/workshops/postgis-intro/knn.html

---
Use recent changes API to update local Wikidata entity mirror.

Need to handle new item, edit, delete, and undelete.

For now we're just interested in items with coordinates, later we might care
about languages, and classes.

At some point we might keep track of redirects.

Deletes
-------
Is the item in our database? If not then ignore it, if yes then delete it.

New
---
Download full entity, check if it contains coordinates, if yes, then add to database, if not then ignore.

Make a note of item ID and revid. Avoid downloading item again during update.

Edits
-----
If the item is in our database and lastrevid is larger than the revid of the change then skip.

Download full entity.

If in our database and latest revision includes coordinates update item in
database. If no coordinates then delete from our database.


======
Currently we have geographic objects represented by the Item class. We also want
information about the type of object, languages and countries.

How about a hierarchy with Item as the base class and GeoItem as a subclass for
geographical objects. We can also have IsA, Language, and Country classes that
derive from Item.

Countries are a subclass of GeoItem.

With the current design the Item table represents a cached copy of the latest
version of the Wikidata item, no history is stored locally. This makes it had to
keep track of changes over time.

The same is true of the OSM data, we just keeping a copy of the most recent
version.

Instead we could store multiple revisions of Wikidata items. We want the latest
version and any that has been considered part of a match with OSM.

Which Wikidata revisions do we keep?

1. latest revision
2. revision used to generate match
3. revision used in match checked by user

Maybe a separate item revision table is too complex. We could just store JSON
from a match in a table of OSM user uploads.

===
All countries have a P625 statement

===
cable-stayed bridge (Q158555)

There are 786 bridges on OSM tagged with bridge:structure=cable-stayed. Some of
these have a Wikidata tag but aren't tagged as a cable-stayed bridge in
Wikidata. The Wikidata could be updated to tag them as a cable-stayed bridge.
Something similar could be applied to other types.

===
Lots of items with coordinates don\'t have OSM tags/keys, either because they
don\'t belong on the map or there isn\'t enough info in Wikidata.

Need to search different properties for OSM tags, at least 'instance of',
'use', 'sport' and 'religion'.

Should start from items with an OSM tag first. Download all items with OSM tag,
then walk subclass tree and download.

===
Test out a new design.

===
Make a status page that shows the size of each database table.
===
What should URLs look like, say I want to show lakes in lapland?

https://osm.wikidata.link/matches?isa=Lake&location=Lapland

===
OSM & Wikidata pin map TODO list

IsA list should support filtering

===
2021-06-17

Candidate list should show street address. For example:

https://alpha.osm.wikidata.link/map/17/40.01461/-105.28196?item=Q42384818
---
Preset could be more specific. For example mosque instead of place of worship.

id-tagging-schema/data/presets/amenity/place_of_worship/muslim.json
---
candidates list should show object tags

===
2021-06-19

* Rename from 'alpha' to 'v2'.
* Use Flask-Babel to for i18n. Get translations from
  https://www.microsoft.com/en-us/language/
* Show total number of items
* Show place name
* Show aliases

===
2021-06-23

Planning to update user IP location code. Should grab items within city or
region. Need to handle IP that only resolves to a whole country. For example
archive.org is 207.241.224.2, and just returns USA. The USA is too big to apply
the matcher interface to.

When trying to match the whole USA we should show the whole country and
encourage the user to zoom in. Once the 

---
Map thoughts. Questions:

What do we show to the user when the site loads?
What happens when the user drags the map?
What happens when the user changes zoom?
How does searching change things?

Starting scenarios:

User enters IP that resolves to a big country, say USA. We show a map of the
whole USA and ask them to zoom in. Once they've zoomed in we can show the total
number of items and the item type facets.

Find item type within Cambridge:

``` SQL
select jsonb_path_query(claims, '$.P31[*].mainsnak.datavalue.value.id') as isa, count(*) as num
from item, item_location, planet_osm_polygon
where item.item_id = item_location.item_id and osm_id=-295355 and ST_Covers(way, location) group by isa order by num;
```

Also need a to show a facet for items where item type is empty

Find item type within California:
``` SQL
select jsonb_path_query(claims, '$.P31[*].mainsnak.datavalue.value.id') as isa, count(*) as num
from item, item_location, planet_osm_polygon
where item.item_id = item_location.item_id and osm_id=-165475 and ST_Intersects(way, location)
group by isa order by num desc limit 20;
```
This query takes 26.5 seconds.

England item count takes 1.5 seconds.

``` SQL
select count(distinct item_id)
from item_location, planet_osm_polygon
where osm_id=-58447 and ST_Covers(way, location);
```

===
2021-06-25

Library buildings (Q856584) in England. Query takes 3 seconds

``` SQL
select count(*)
from item, item_location, planet_osm_polygon as loc
where loc.osm_id=-58447
    and jsonb_path_query_array(claims, '$.P31[*].mainsnak.datavalue.value.id') ? 'Q856584'
    and item.item_id = item_location.item_id
    and item_location.location && loc.way;
```
===
2021-07-04

TODO
* Better error page than just 500 Internal Server Error.
* Improve handling of Wikidata items without coordinates. Use different colour
  for OSM Pin. Explain situation on item detail page. No need to look for matches.
* DONE: Show spinner when looking for nearby OSM candidate matches.
* DONE: Show message if no matches found.
* Add 'building only match' switch
* Two item pins on top of each other is a problem.

2021-07-05

Sometimes the selected OSM matches are incorrect. For example:

https://v2.osm.wikidata.link/map/15/37.31390/-121.86338?item=Q83645632

The item is linked to a node, a way and a relation. The node shows as a pin on
the map, but isn't in the list of possible nearby matches. The way and relation
both show in the list, but aren't selected.

2021-07-07

Logout link should come back to the same map location. Need to record the
location somewhere. Could be in a cookie, constant updating of the logout
URL, or have JavaScript that runs when the user follows the logout link.

Search
Should show a spinner so the user knows something is happening.
Trigger search after first three characters have been entered.
DONE: Style search hits so not so close to search box

Highlight chosen search result.
Close button to hide search results.
DONE: Zoom to result bounds instead of zoom level 16.
Should you be allowed to search while editing?

DONE: Hide OSM candidate checkboxes if user not logged in.

2021-07-10

Exclude ways that are part of a boundary. Example:

https://v2.osm.wikidata.link/map/18/42.37903/-71.11136?item=Q14715848

2021-07-16

Need better handling for OSM with wikidata tag but item has no coordinates. 

Viewing a street shows too many yellow pins.
https://v2.osm.wikidata.link/map/15/37.31221/-121.88869?item=Q89545422

2021-07-17
Could match on just name
https://v2.osm.wikidata.link/map/18/50.21789/-5.28079?item=Q5288904

2021-07-18
Florida State Road 922 (Q2433226) is stored as multiple lines in the osm2pgsql
database. Need to rebuild the database with the --multi-geometry so there is
only one.

2021-07-19
After a save clicking on another item without closing edit panel causes
problems. Need to trigger close_edit_list when opening item if upload_state is
set to 'done'

2021-07-22

Example of a long road: Collins Avenue (Q652775)
https://v2.osm.wikidata.link/map/19/25.86222/-80.12032?item=Q652775

2021-08-04
Use https://vue-select.org/ for item type filter.
Show alert with spinner while count is running.
Maybe we want to supply the item type filter as JSON and filter in the browser,
no need to hit the server and database.
Write documentation for the API.
Speed up the item detail OSM nearby option.
Use the sidebar to show list of items in the current view, so the user can
go through the list and check them.
OSM object polygon size is broken

2021-08-05

IsA search

```sql
SELECT 'Q' || item.item_id, item.labels->'en'->>'value' FROM item WHERE
item.claims ? 'P1282' AND lower(jsonb_extract_path_text(item.labels, 'en',
'value')) LIKE lower('%hotel%') AND length(jsonb_extract_path_text(item.labels,
'en', 'value')) < 20;
```

2021-09-11

Notes from Pixel 2

Pin at the centroid of a polygon is to busy, especially with an item that links
to multiple OSM objects. Object outline already on map, just need to connect
outline to Wikidata markers. Could try and work out corners of rectangular
buildings. Should link to ends nearest node for linear objects.

Show warning when navigating away from map with edits.

See WindowEventHandlers.onbeforeunload

Option to clear edit list.

---
Ignore coordinates with a Google Maps reference. Example:

https://www.wikidata.org/w/index.php?title=Q66228733&oldid=992964237

---
Check history for previous wikidata tags to warn mappers if a wikidata tag
they're adding has previously been removed.

Examples:
    https://v2.osm.wikidata.link/map/17/52.18211/0.17756?item=Q6717455
    and https://www.openstreetmap.org/way/143741201
    https://www.openstreetmap.org/way/684624781

---
What happens when we moved the map?

First we check the area visible on the map. If it is too large then there is
nothing we can do, we give up and tell the user they need to zoom in.

Otherwise we send the server a request for a count of the number of items in the
current view. If the count is too high we abort and tell the user to zoom in.

Once we know the area isn't too big and doesn't have too many items we want to
make three requests to the server. First we make requests for the Wikidata items
on the map another request for OSM objects with a Wikidata tag on the map. Both
requests run at the same time. Once both requests complete we make another
request to check for missing Wikidata items that were linked from OSM objects.

---
This is done

https://v2.osm.wikidata.link/map/18/52.23270/0.21560?item=Q55099320
should match: https://www.openstreetmap.org/node/2000849525

Look for Tag:abandoned:railway=station

---
Need better handling for Wikidata redirects.

Example: https://www.openstreetmap.org/way/130458959
https://v2.osm.wikidata.link/map/18/51.36973/-2.81079?item=Q5117357

---
Consider 'OS grid reference' 
https://www.wikidata.org/w/index.php?title=Q27082051&oldid=1336630735

---
Check for OpenStreetMap relation ID (P402) in Wikidata

Display on details page. Highlight matching relation.

example: https://www.wikidata.org/wiki/Q78078847

---
TODO

* DONE: Add special code for matching watercourses that works like street matching
* DONE: Frontend should catch API errors and show them
* DONE: API calls should return errors in JSON

* Run update code from systemd
* Stop Wikidata update code from crashing when it hits an error
* Add an option for 'select all' for linear features
* Add a note to details page explaining street matching
* Upload code to GitHub
* Candidates list jumps when first object is selected, because message appears
    at the top the list. Can be fixed by having a message there and replacing
    it.

IsA pages
* Flesh out IsA pages
* Allow users to add extra tags to IsA
* Add option to update IsA

Type filter
* Include type filter QIDs in URL
* Move type filter to modal box
* Show item type description

---
Show note about relations for tram stops and windfarms

---
Show  dissolved, abolished or demolished date (P576) 
https://map.osm.wikidata.link/map/18/40.74610/-73.99652?item=Q14707174

---
Get subclasses for one item type

``` SQL
select item_id, labels->'en'->'value' from item where jsonb_path_query_array(claims, '$."P279"[*]."mainsnak"."datavalue"."value"."id"'::jsonpath) ?| '{"Q718893"}';
```

Get subclasses for items with OSM tag/key

``` SQL
select item_id, labels->'en'->'value'
	from item
	where jsonb_path_query_array(claims, '$."P279"[*]."mainsnak"."datavalue"."value"."id"'::jsonpath)
		?| array(select 'Q' || item_id from item where claims ? 'P1282');
```

---
Shipyard results shouldn't include place=city
https://map.osm.wikidata.link/map/18/50.89540/-1.38243?item=Q551401