Hacker News Reader

Comment by benp84 | Hacker News Reader

Congrats on the success! I'm curious: the condition of <1 mile proximity isn't transitive, so wouldn't users be seeing only one half of a lot of conversations? Like if A was close to B, B was close to C, but A wasn't close to C, then A would only see what B says to C but not what C says back. Or have you divided up space into fixed cells roughly one mile wide to prevent this?

View on HN

This was probably my most embarrassing oversight. Your first point is the way it's working. I'm trying to figure out if there's a way to make that work without segmenting the map into fixed cells... any thoughts?

You should just make the text from 1 to 2 miles show at 50% alpha, and the 25% alpha from 2 to 3 miles.

Does this really solve the problem though? What happens if someone 3 miles away is talking to someone who's 1 mile away from themselves, but 4 miles away from you? Then you'd see the transparent text of them talking to some person you can't see messages from, yet also see transparent text of them responding to people you can see messages from.

I personally don't see how you could completely avoid this without some kind of fixed regions, unless you required people to do some kind of an "@user Hey..." for every message so that you would know if you share the same sphere with the destination user. This makes it more tedious and less fun, though, plus it takes away the whole idea of multicasting.

That is how it is working in real life. You can hear the person closer to you speaking, but not the one farther

This sounds like a solid and scalable approach, most others that come to mind relate to being able to join a conversation based on seeing part of it and then being added, but if the app isn't doing identity-based messaging (e.g. if A replies to B does it become more like tweeting at each other?) then there's no real way to do so.

Another nice aspect of keeping it strictly distance-based is that it makes it simpler to scale - all persons within a geographic region are able to see only other people within that region, so within limits you can run separate backend instances as required.

And of course there are all sorts of potential growth directions by allowing communities (e.g. "Students at XYZU and people within 1 mile" or "Students at XYZU who are within 1 mile").

I don't think it's a simple problem, but it is interesting.

You might try a clustering algorithms like k-means. Or perhaps there is a graph theory way to approach it.

But I suspect every solution you come up with will involve some trade offs, so there is something to be said for the simple solution you implemented.

I haven't used the app because I have an android phone so I don't know how it works, but is there any way to have someone outside of the 1 mile radius ask to "join" people within another radius? Or would that break the idea of the app.

Keep in mind that users are logging on and off all the time, so it has to be an online algorithm.

I think that if User A "replies" to User B, you then allow anyone who can see either party to see both parties, at least in that one conversation.

To detect replies, one option is to do a statistical analysis of the typical time between two messages on the network. Anyone who replies in the upper 70% percentile is "replying"

You could make the effect fuzzy and have a back and forth conversation (which would probably be obvious in the data) have a stronger effect and could use that for training your algorithm.

This is a really great solution.

I can't think of any other way off hand. I'm assuming you don't like cells because of edge cases where two people could be near each other but in different cells? If the cells were carefully selected it might not be too big of a problem. For example, you could put each college campus in its own cell. But that could take a while and you'd have to drop the one-mile guarantee. I'll let you know if I think of anything else. I don't think it has to be a dealbreaker for an otherwise great idea!

ok sweet! just keep me updated. im all ears.

EDIT - dugmartin explained it better below ...

Maybe, something similar to hearing, a person who is closer is louder while the one far is faint.... So nearby people have a stronger font while the one who is far has a lighter font ? Note - I've not used this app, so don't know how it is working ...

Is there a reason it requires iOS 7? Those with jail broken iphones might still be on 5...

Reply on news.ycombinator.com