Can I port this to Python?

[scoofy]

Hi, i just came across your code here, and am working on something similar in python. I was going to try to port this, if that's fine with you, and i may need some assistance along the way.

Let me know what you think!

[bocops]

Hi Matt. Definitely, feel free to port this and reach out to me with all questions you might have.

If you create a repo for your port, I'll add a link to it somewhere. :)

EDIT: CONTRIBUTING.md has instructions on how this might work best for both of us.

[scoofy]

Okay, i'm making progress, but i definitely understand Java less than i thought i could intuitively understand. First couple of questions are this:

1. It appears you are calling the open location code arguments in your methods "olc," if this is correct, it will cause a problem on the python end as the standard python import for openlocationcodes is "from openlocationcodes import openlocationcodes as olc." This isn't a problem, per se, but could cause some conflicts going back and forth. I may rename the argument "open_location_code" or "plus_code". Is there something i'm missing?

2. So, the entirety of the code is one large class. I know this is standard for java, but it's not for python. If there is any reason why i should have it structured as class, rather than as standard library, let me know.

3. Okay, this not really a question. There is literally not an "isPadded" function in the Python version.... what the hell?

[bocops]

1. You are correct, I'm using olc as name for objects of the OpenLocationCode class throughout. You should be safe to use any other name that makes sense, if olc itself doesn't work.
2. I'm not entirely familiar with how things are done in Python - but it seems as if the original OLC implementation in Python doesn't use a class, either, so doing it that way should work.
3. This is strange indeed - however, the isPadded function in Java just checks whether the OLC string contains the defined padding character '0', so you should be able to write the appropriate function yourself.

[bocops]

Yes, Java allows for multiple constructors without one needing to be the "primary" one. It often makes sense to call one constructor from another to avoid code duplication internally, but that isn't strictly necessary. The various constructors here somewhat mimic the ones of the original OLC implementation.

Specifically, there are three constructors that take a location (as either an object of the OpenLocationCode class, a plus code string, or simply latitude/longitude coordinates) and a valid tile size - which, as you understood correctly is just an internal enumeration corresponding to the number of characters used for the eventual tile address. These are constructors 2, 3 and 5 from your list above.

The other two constructors either just create an object from an already existing tile address (#4) - or try to work out the intended tile size from the padding that might exist in the underlying plus code (#1).

If Python only allows one constructor, it would probably be sensible for that constructor to take plus code string and tile size as arguments (the final one, as you already pointed out), and then create additional functions to call if you have other arguments - for example:

@classmethod
    def createOGTFromCoordinates(lat, lng, tilesize):
        //First, get plus code matching lat/lng coordinates, then
        return OGT(pluscode, tilesize)

(Again, I'm not sure how Python generally handles these things, so this might be wrong on different levels)

To find out why the original OLC implementation for Python isn't a class in the first place, you can try asking on the original repo, although it isn't really that active at the moment.

[scoofy]

Okay, I've ported OpenGeoTile.java to python, and am going to do a bit of cleanup and then start working on porting the tests you wrote. I however, have stumbled onto a bit of confusion though. When i forked your code, these files also showed up... but they aren't in your version on your page. Maybe i'm just dumb in that i don't know what's going on here, but i'm not too proud to just ask...

What are these extra files? Are they still included in your code? Where did they come from? I can easily port them, i'm just confused:
Coordinate.java
MergingTileArea.java
SimpleTileArea.java
TileArea.java
TileAreaPolygonalBuilder.java

[scoofy]

I can see that i'm integrating each of these as i port all the tests

[bocops]

Those files exist in a separate branch and haven't been added to the main branch yet. That branch has become stale, because I haven't found any immediate need for myself.

I played around with the idea of having sets of tiles to allow for areas with other shapes than just a single rectangle. This could be useful to represent some area (say, a city) as a list of geotiles down to some precision, allowing to check whether some location is inside city borders or not.

I don't consider any of it to be final, the classes are mostly experiments to see what works and what doesn't - but if you want to port any of it, you're of course free to do so. The best comments exist in the abstract TileArea class, while the most useful implementation probably are MergingTileArea (to construct an area from geotiles) and TileAreaPolygonalBuilder (to construct an area from a polygon of coordinates.

[scoofy]

Alright, i need to write tests for the TileArea and SimpleTileArea classes, but i've ported them. This has been really fun!

I think i've come up with a very simple system, i might iterate on in the next few days, and i haven't tested it, but the TileArea now has a function called "getShortestCoveringTileList" which merges all smaller tiles into the max sized possible tiles. I'll probably add this to the constructor and method for adding tiles.

This seems to me to be better than rasterization, as scaling everything to the minimum number of tiles, instead of arbitrarily large numbers of tiles, will lead to massively reduce calculations when comparing two areas. It's simple to understand as:

assert A.contains(B) or B.contains(A)

for each A tile in Area A and B tile in Area B.

take a look and let me know if you have any questions