# Questions tagged [graphs-and-networks]

Questions about handling graphs in Mathematica, graph theory, graph visualization, GraphPlot, the built-in Graph type and the Combinatorica` package.

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### Strange Vertex Size Problem when Moving From 999 to 1000 Verteces

I have a problem with Graph plot scaling of vertex sizes when I go from 999 vertices to 1000 vertices. The following code scales the vertex size properly when the numNodes = 999; but not numNodes = ...
188 views

### Restores a difficult digraph

I want to reconstruct this picture,like this: I have do some work,this is my code ...
47 views

### Adding an edge between G1 vx and G2 vy?

I have two random graphs G1 and G2 that I want to join with an edge from a particular vertex vx in G1 to a particular vertex vy in G2. I can't find a way to do it. Here is my latest code: ...
366 views

### Can Mathematica read planar graphs with pc format?

We can download files about some special planar graphs at the following website, but their files are suffixed with pc. http://users.cecs.anu.edu.au/~bdm/data/planegraphs.html I don't know how to ...
163 views

### Finding connected components in 2D integer coordinate system

Let L be a finite set of pair of integers. I want to partition L according to connectivity The connectivity is intuitive : Rule1 ...
86 views

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1 vote
60 views

### NestGraph Basics

Summary How does NestGraph build a graph? Example Column[NestList[{2 #, 2 # + 1} &, 0, 2]] 0 {0, 1} {{0, 2}, {1, 3}} Now NestGraph[{2 #, 2 # + 1} &, 0, 2, ...
48 views

### Mathematica failing to export consistent layout

Mathematica is a great tool but when it comes to layout generation is quite poorly intuitive: I would love that exporting to images and SVGs could be more friendly and compliant with graphic design ...
98 views

### Can you count the number of self-loops per vertex in a graph?

In this graph, such output would be: 0 self-loops for vertex w, 1 self-loop for vertex c, 6 self-loops for vertex ...
77 views

### Need some Graph Invariant Computations

I have found a list of graph invariants at the house of graphs (HOG) here. I am able to compute almost all of them with Mathematica and IGraph/M. I am missing computations for the following: Genus, ...
1 vote
78 views

### GraphUnion in Mathematica 12 vs 13

In Mathematica 13, GraphUnion[g] returns g. In Mathematica 12, in what I can only think is a bug, the same code returns ...