I'm making a network visualization with NodeXL. My graph includes several nodes that have no edges but that I would still like to display- but it doesn't appear that these nodes show up when I show the graph. Does anyone know how to include these 'isolated' nodes in the visualization?
I've run into this problem as well and have not found a "built-in" solution that exists inside NodeXL. One (poor) solution is, when you import or add your edges to NodeXL, add one additional row to your edgelist for each isolated node you wish to appear, with the two values (2,2) for example, if you wish to force NodeXL to show unconnected node 2 in your network graph. This node WILL appear in your network image, albeit with a circular "loop" from that node to itself.
Related
I read a couple of posts on position nodes in force layout but didn't find an answer to what I was looking for.
I have an object with nodes and links.
I' trying to create a graph which would show all the nodes top to bottom.
I was looking at the example code from here:
https://github.com/danielstern/force-graph-example
Here's a screenshot of the result:
I'm trying to find a way to position each node so the nodes without parents would be on the top and the ones connecting to them would be under them and so forth.
Here's an image to illustrate it:
Right now, all the nodes are scattered randomly.
I wanted to if I need to actually calculate the position of each node in a vertical view or is there a smarter/built-in way to achieve it.
I looked at this example which looked promising:
How to organise node positions in D3 Force layout
But in my case I don't have a way to differentiate between nodes levels so I don't think the yPostion would help.
I was also looking at thes post:
d3.js - How can I expand force directed graph horizontally?
According to #Lars Kotthoff:
"The point of the force layout is to automatically lay out a graph like this so that you don't have to specify the positions of the nodes yourself".
Since my graph is not really a tree, I don't think the tree view would match.
What would be my best approach to position the nodes?
Or perhaps there's a better library to achieve what I need?
I found this package:
d3-dag
It basically supports what I need:
"Often data sets are hierarchical, but are not in a tree structure..."
Here's an exmaple:
exmaple
I've spent hours searching for an answer to this, but in most cases either the
question is about plots/charts (rather than graphs as in "control flow graph"),
or the answer "just use graphviz" is a valid answer.
However I have some constraints and requirements that make "just use graphviz" a
non-answer.
The full graph is large enough that it's not possible to generate a graphviz
for all of it.
Nodes and edges will be dynamically added and removed.
Nodes have lots of information that will be hidden by default and will be
expanded on request (imagine every node as a table with expandable rows/cols)
I want to be able to show only a subset of the graph on request, e.g. for
features like "only show reachable part of the graph from this node" or "show
all simple paths from this node to this node".
Basically I want to be able to start drawing nodes and edges on a 2D plane, and
add new nodes and edges dynamically. It's fine if nodes/edges move around as new
stuff is added. While I don't yet have hard requirements for this, it'd be good
if it looked "nice" -- for example if a node has lots of incoming edges (this is
a directed graph) ideally it'd be in a central place on the plane with all other
nodes around it etc.
Anything that gets me going would be helpful. Thanks.
(I don't know what label to add to this, adding "graph-theory" because I don't know what else to add)
I am using go js to draw diagrams by drag and drop , i want to draw a network diagram for that I used GO js and used ForceDirectedLayout , but the problem is my nodes are overlapping on each other but i dont want that. is there any way to dont allow to overlap nodes on each other in ForceDirectedLayout.
It is impossible for ForceDirectedLayout to guarantee that no nodes overlap each other, but in order to decrease the chance of overlaps, you could increase its values of maxIterations and defaultElectricalCharge.
https://gojs.net/latest/api/symbols/ForceDirectedLayout.html#maxIterations
https://gojs.net/latest/api/symbols/ForceDirectedLayout.html#defaultElectricalCharge
If your nodes are unusually large, you might also want to increase the value of defaultSpringLength.
https://gojs.net/latest/api/symbols/ForceDirectedLayout.html#defaultSpringLength
I have a MetroManila.osm file and i parse it so it can read roads only using this command: --keep = --keep-nodes=highway --keep-ways=. Is this the right command for filtering only the roads? What i want after parsing is to create a node where there's intersections or curves, or is it possible with just using the whole nodes in MetroManila.osm? Can i create an edge using it and how do i do it? Currently, i'm really lost on what to do since i'm fairly new on android studio and in osmdroid.
This hasn't really anything to do with Android or osmdroid.
For learning how to create a routing graph from an OSM file see the related answer at help.openstreetmap.org. Quoting from it:
parse all ways; throw away those that are not roads, and for the others, remember the node IDs they consist of, by incrementing a "link counter" for each node referenced.
parse all ways a second time; a way will normally become one edge, but if any nodes apart from the first and the last have a link counter greater than one, then split the way into two edges at that point. Nodes with a link counter of one and which are neither first nor last can be thrown away unless you need to compute the length of the edge.
(if you need geometry for your graph nodes) parse the nodes section of the XML now, recording coordinates for all nodes that you have retained.
Also take a look at routing in the OSM wiki to get some general hints and existing tools and libraries.
Regarding osmdroid: If you don't rely on offline routing then take a look at osmbonuspack, it supports online routing.
If you don't want to reinvent the wheel then just use one of the existing offline routing tools mentioned in the OSM wiki.
Say we have a graph that is similar to a linked list (or a directed acyclic graph). An independent set consists of nodes that don't share edges with any other node in the set. If each node is weighted, how can we calculate the max possible value of the independent set of nodes? I understand we have to use Dynamic Programming so I have a slight clue but I'm hoping someone could explain how they would approach it. Thank you!
I believe that this problem is NP-hard for arbitrary directed acyclic graphs. The corresponding problem for undirected graphs is known to be NP-hard, and that problem can be converted into the directed version of the problem by directing all of the edges in a way that makes the resulting graph a DAG. Any independent set in the original graph will be an independent set in the directed graph and vice-versa, so any solution to the directed case will solve the undirected case.
Your question talks about solving this problem on a linked list. If you're solving the problem just for linked lists, there is a polynomial-time solution using dynamic programming. As a hint, if you choose one node in the linked list, you have to skip the next node, then should maximize what remains. If you don't choose the node, you just maximize the value of the rest of the list. Taking the better of these two options and evaluating this bottom-up will give you a really fast DP algorithm.
Hope this helps!