Re: [PLUG] Topics for PLUG in January

[phreak--- via plug <plug@lists.phillylinux.org>]

    On 1/3/2022 10:29 AM, Walt Mankowski via plug wrote:
> ...
>
> Step 1 in solving it is realizing you can think of the grid as a graph
> where each number is a node, and the edges are each cells
> neighbors. Once you've done that, there are a number of different
> shortest path algorithms you can use. One of the most popular is
> called Dijkstra's Algorithm, and some friends mentioned that they had
> to look it up and see how to implement it. All I did was load all the
> edges into networkx (another Python graph module) and then call
> nx.dijkstra_path_length().
>
> 1. https://adventofcode.com/2021/day/15
>     
    A couple years ago, I experimented with GraphViz and some tools of
    the like that allow generating graphical representations of graphs,
    using a PHP library for it.

At the time, I was interested in analyzing properties of graphs and the different relationships that existed (degrees of separation, density, min/max in/out degrees, different average properties) in real world models.

The cumulative result was a site I set up which allows the public to easily model graphs: https://graph.interlinked.us/

Anyone can create a graph model by adding nodes and relationships using the web tool, and it'll use common graph algorithms to generate all the different statistics, which is mainly what I was interested in at the time - network properties. For instance, I see this for a graph where I modeled some social relationships:

Vertices (N)26

Edges (M)67

Connected Components1

% in Largest Connected Component100%

CompleteNo

# of Groups1

Density (Undirected)0.20615384615385

Density (Directed)0.10307692307692

Min Degree1

Max Degree25

Min In-Degree k_in1

Max In-Degree k_in12

Min Out-Degree k_out1

Max Out-Degree k_out13

Avg In-Degree k_in2.5769230769231

Avg Out-Degree k_out2.5769230769231

The graph on the home page is generated by GraphViz, but it's not a real model, just an example of what it could look like.

Not sure if this is helpful or of interest, but maybe an easy way to play around.

Albert

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