A5
Languages and libraries
geospatial indexing library
SHOW HN2025
How HN took it
2 positive, 9 neutral or asking, 0 mixed, 2 critical, out of 13 comments about the project. Thread score -0.09.
Design: 1 for, 1 againstIdea: 0 for, 1 against
The thread, comment by comment
Each row is a top-level comment and its replies, in HN's order. Select a cell to open that comment on HN.
positive neutral or mixed critical about another commenter or something else the maker
What HN said
What people liked
Equal-area cells are valuable in practice
From 1 comment
Yes, those are the obvious ones. This example: https://a5geo.org/examples/airbnb shows why the equal area is valuable in practice, while https://a5geo.org/examples/area shows the…
pheelicks on HN
Interesting aesthetics and approach
From 1 comment
Haha that colour scale on the area variance page makes it a bit hard to see whether nearby H3 hexagons are very different in size...? I've never really investigated, but my…
carderne on HN
Objections
Irregular shapes and non-uniform centroid distances are downsides
From 1 comment
Can you give some examples of when this might be better to use than H3? The ones that seem obvious: - You need very high resolution. H3 is also 64 bit I think, but it seems like…
carderne on HN
Dodecahedron optimisation seems an uncommon need
From 1 comment
> The benefit of choosing a dodecahedron is that it is the platonic solid with the lowest vertex curvature, and by this measure it is the most spherical of all the platonic…
ralusek on HN
Only a TypeScript implementation so far
From 1 comment
H3 and S2 are supported out of the box in ClickHouse and have reference libraries in C and C++. But it looks like A5 only has a reference implementation in TypeScript. Porting…
zX41ZdbW on HN
Title lacks a description
From 1 comment
Please please please include a description in your title. Just a couple of words will do.
knowitnone on HN
Requests
Ports to other languages such as C and C++
From 1 comment
H3 and S2 are supported out of the box in ClickHouse and have reference libraries in C and C++. But it looks like A5 only has a reference implementation in TypeScript. Porting…
zX41ZdbW on HN
Show next-higher and next-smaller overlay like H3 landing page
From 1 comment
The description of the algorithm notes that each irregular pentagon is divided into four sub-pentagons. Eyeballing the maps, I don't see any group of 4 pentagons forming a…
i3oi3 on HN
Questions
Advantage over HEALPix
From 1 comment
What's the advantage of this over HEALPix projection? https://en.wikipedia.org/wiki/HEALPix
xioxox on HN
Why use it instead of H3
From 1 comment
Can you give some examples of when this might be better to use than H3? The ones that seem obvious: - You need very high resolution. H3 is also 64 bit I think, but it seems like…
carderne on HN
Is it useful beyond visualization, e.g. database performance
From 1 comment
Is it primarily useful just for data visualization? Would there be an potential performance benefits for something like searching a database for nearby data?
Bedon292 on HN
Alternatives named
H3
From 2 comments
A5 uses pentagons, Uber's H3 uses hexagons: H3: Uber’s Hexagonal Hierarchical Spatial Index https://www.uber.com/en-DE/blog/h3/
jll29 on HNCan you give some examples of when this might be better to use than H3? The ones that seem obvious: - You need very high resolution. H3 is also 64 bit I think, but it seems like…
carderne on HN
S2
From 2 comments
Also check S2: http://s2geometry.io/, created at Google before H3, which uses squares and underpins the fast indexing in BigQuery amongst many other things
pheelicks on HNSo if I've understood correctly: Google's S2 is all about performance and prefix-matching. Uber's H3 makes the math a bit more complex to prioritize less variation in…
yencabulator on HN
HEALPix
From 1 comment
What's the advantage of this over HEALPix projection? https://en.wikipedia.org/wiki/HEALPix
xioxox on HN