I am new here.. MY Question :
i have used KKLayout for visualization a graph. The Graph is created in while-Loop (after each iteraion) after a new Calculation and every time the vertices is placed on random Locations/Postions. I want to fix them, so that they placed on same Position after each Loop-Iteration. How can i fix them ???? thanx
By default, the force-directed layouts start with their vertices in random positions; this is why you're seeing this behavior.
There are a couple of different approaches that you can take to resolving this issue.
(1) Use the Layout.setInitializer() method to specify a consistent starting position for each vertex. This will ensure that KKLayout always does the same thing.
(2) If there is a specific layout result (set of positions) that you like, you can use StaticLayout initialized with those positions. PersistentLayoutImpl can be useful for serializing/restoring those positions if desired.
Related
I'm trying to render a tree that is very broad... and it renders, as expected, in a long, skinny horizontal image.
Problem is that I need a graph suitable for a document. I would very much like to take and move the nodes that are rendered horizontally and "drag" them down so that the graph is more vertical... with the edges curving to accommodate this. Are there any clever ways to accomplish this? GraphViz settings? Third party tools that let me manipulate and fine tune the output? I work mostly in the Python ecosystem, but open to others. Also open to the use of tools like Visio and other pro drawing tools. Thanks!
Edit
After implementing the answer below by #sroush, and then tweaking a little further with Photoshop, got some nice results.
Tweaking the above in Photosop. Had to add the two curved edges after the secondary node by hand, but it's worth it. Much more presentable.
I assume you are using dot, and your graph "naturally" has only a few ranks (rows).
There are a few tweaks that will help a bit (reducing node horizontal footprints):
node [shape=rect] // snugger fit into rectangles
insert newlines into node labels e.g. xxx [label="Controller Board\n#19_8"])
Also try the unflatten program (https://www.graphviz.org/pdf/unflatten.1.pdf). It will increase the apparent number of ranks (rows).
See related question here with command line examples:
Distribute nodes on the same rank of a wide graph to different lines
You can use the minlen property to limit the minimum level span of some edges.This avoids the result becoming very long in the horizontal position.
For example:
digraph {
a->b
a->c
a->d
a->e
}
This will output the following image:
But when minlen is used, the picture will become longer vertically but shortened horizontally:
digraph {
a->b
a->c
a->d[minlen=2]
a->e[minlen=3]
}
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'm using the Overpass API to query Open Street Maps for nearby road segments. I am pretty sure that my query is returning all of the nodes of the nearby way... but I only want nearby nodes of the nearby way.
In the documentation it references this problem:
In general, you will be rather interested in complete data than just
elements of a single type. First, there are several valid definitions
of what "complete map data" means. The first unclear topic is what to
do with nodes outside the bounding box which are members of ways that
lie partly inside the bounding box.
The same question repeats for relations. If you wait for a turn
restriction, you may prefer to get all elements of the relation
included. If your bounding box hits for example the border of Russia,
you likely don't want to download ten thousands kilometers of boundary
around half the world.
But I looked at the subsequent examples and didn't see the solution.
Basically, in their example, how would I restrict the elements returned to those strictly in the bounding box (rather than returning the whole boundary of Russia)?
My current query is
way (around:100,50.746,7.154) [highway~"^(secondary|tertiary)$"];
>;
out ids geom;
I'm thinking maybe I need to change it to node (around:...) and then recurse upwards to the way to query for the highway tag but I'm not sure if I am even on the right track.
Actually, it's even a bit more complicated, as you need the set intersection of all nodes in a 100m distance and those nodes belonging to one of the relevant ways. Here's how your query should look like: Adjust distance, tags for ways as needed.
Note that depending on the tagging, there's no guarantee that you will find a node in a certain distance, especially if roads tend to be rather straight and longish. This for sure will impact your results, so a bit experimenting with a suitable radius is probably needed.
// Find nodes up to 100m around center point
// (center is overpass turbo specific for center point lat/lon in current map view)
node(around:100,{{center}})->.aroundnodes;
// recurse up to ways with highway = secondary/tertiary
way(bn.aroundnodes)[highway~"^(secondary|tertiary)$"]->.allways;
// determine nodes belonging to found ways
node(w.allways)->.waynodes;
(
// determine intersection of all ways' nodes and nodes around center point
node.waynodes.aroundnodes;
// and return ways (intersection is just a workaround for a bug)
way.allways.allways;
);
out;
check it out in overpass turbo: http://overpass-turbo.eu/s/hPV
I'm trying to plug a (very) simple graph layout algorithm into my GEF editor. I do it by simply adding calculateX() and calculateY() methods to my NodeEditParts' refreshVisuals() (the graph figure has an XYLayout obviously).
It does work, albeit only for those nodes, which have a connection to another node, of which they are the source. When I try to access the constraints for nodes to which the node in question has a connection, of which it is the target, I get a NullPointerException.
I'm guessing that this is to do with the order in which nodes are drawn in GEF.
I'm also guessing that there is no such thing as an element parser checking which elements will have to be drawn first, but rather that elements are either drawn in the order they appear in a List, or concurrently via the EditPartFactory (which, however, must get its input from some sort of ordered collection in the model).
But how is it really done?
In GEF the elements are drawn in the order they appear in the list returned by getModelChildren() (I don't remember if from start to end or backwards, but you can check the code)
Nevertheless, I couldn't understand what exactly was your problem, so if you can provide more details I may help you some more.