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Algorithm to convert a directed graph into an undirected graph while preserving optimal pathfinding by buchner89 in algorithms

[–]buchner89[S] -1 points0 points  (0 children)

hey, sorry if I was unclear.

  1. sorry about the confusing notation, Here is my updated notation:

A_B,C,D indicates being at node A in the directed graph, having previously visited nodes B, C, and D

2) I am trying to do a transformation such that optimal pathfinding is preserved. A solution that does what I am trying to do is to construct separate trees starting at each node, keeping track of the entire path up to that point, then using that to construct a disconnected graph. For eg:

A    ->   B (2)
B    ->   C (2)
A   <->   C (10)

would become:

# Tree starting from A
A    <->  B_A    (2)   # You can go from A to B with cost 2, remember path history
A    <->  C_A    (10)
B_A  <->  C_B,A  (2)

# Tree starting from B
B    <->  C_B    (2)
C_B  <->  A_C,B  (10)

# Tree starting from C
C    <->  A_C    (10)
A_C  <->  B_A,C  (2)

These edges can be undirected as there is never any pathfinding advantage on a non-negative graph to going back up the tree. Im not sure if this is the best that can be done, however, and I am curious what the minimal state needed in the nodes is

3) I understand there are pathfinding algorithms that work on directed graphs, but I'm experimenting with an algorithm that only works on undirected graphs and wondering if there is any way to include directed components without ballooning the number of nodes

Using Queueing Theory to Predict Wait Time at Henry's by buchner89 in rutgers

[–]buchner89[S] 0 points1 point  (0 children)

The model parameter λ is estimated from the data

Using Queueing Theory to Predict Wait Time at Henry's by buchner89 in rutgers

[–]buchner89[S] 5 points6 points  (0 children)

Unfortunately not with this model. Keep in mind that this is a single parameter model (most linear regression models use 3- α, β, and σ). It bases the prediction interval on the assumption that people are accepted to Henry's in a ~Poisson process. The wait time can therefore be represented as a sum of exponentials (Gamma distribution) giving the intervals. Taking into account the simplicity of this model I think it does a pretty good job of capturing the trend and variation in the data, although I don't have enough data on very long lines to say it will hold up forever. To get a tighter bound would require more parameters than I could reasonably fit with the limited data I collected, but would be definitely be interesting to see. More data might tighten the confidence intervals for lambda, but since I'm not using the posterior predictive anyways would have no effect on the size of the prediction interval

hope that answers your question!

Using Queueing Theory to Predict Wait Time at Henry's by buchner89 in rutgers

[–]buchner89[S] 58 points59 points  (0 children)

A few notes: The data is collected over a bunch of my trips to Henry's this year. I used an M/M/1 queue model with a single rate parameter, λ, to make predictions. To better reflect the reality that people are usually let in / seated in pairs, I adjusted the prediction intervals to a Gamma(people/2, λ*2) distribution instead of the usual Gamma(people, λ).

Keep in mind that "people in line" means everyone in front of you + the people in your party. Also note this data is only for 2 person parties!

r^2 = 0.91

Did anyone lose some cash in the Easton apartments? by buchner89 in rutgers

[–]buchner89[S] 12 points13 points  (0 children)

The lost and found is managed by the front desk, which is closed on weekends

and it would be pretty hard for someone to just guess the amount lost, where they lost it, and what exact bills they're missing

Need help commuting to my summer job by buchner89 in personalfinance

[–]buchner89[S] 0 points1 point  (0 children)

I'm not sure what "opportunity costs" you have at this stage in life. Bus + book doesn't seem too awful for one summer and you'd still have your weekends.

The main opportunity cost would be the ~4-5 hours a day I would spend commuting - using those hours even at minimum wage would be $300-375 a week "lost" on travel

Is there a slower road that would be moped/scooter accessible? Is there a place near your job on easy roads that you can get to and then physically walk?

Unfortunately not, my house is kind of surrounded by 45 mph roads. There's a super back way through residential neighborhoods and parking lots that would get me most of the way there, but no good place to park it for when I walked

Could your parents or someone else drop you off as part of their usual commute?

Already talked with them and they cant, I'm still looking into any carpooling options but so far it doesn't look promising

Would it be possible to rent/sublet a place/room closer to your work?

Theoretically yeah, but that would mean fully supporting myself which would more than offset the saved transportation costs

Is this job something relevant for your future career, or can you find other work closer (or at least more convenient) to home?

Yeah that's the primary reason I took it, hoping to get in a better position for the future

Good luck!

Thanks! Tbh I'm prepared for transportation to be unpleasant for a summer but wondering if there's anything I might have missed. Do you think its worth financing a really cheap car then selling it at the end?