zoom/pan/scroll force directed network in amcharts4 library - javascript

I want to use amcharts4 to display a network with a huge number of parent nodes and even more child nodes. I took one of the examples found on the amcharts website and increased the number of child nodes on multiple parent nodes. The nodes expand to a point where they bounce off the browser screen and become unreachable. I am a looking for a way to navigate the network by zooming and panning in order to reach the nodes that are outside of the browser page.
I found similar questions on stackoverflow but they were mainly related with XYCharts and maps where ZoomControl was used on the chart/map object and the zoom property was enabled. I couldn't use this method on the force directed diagram element that I have in my code.
Kindly help me out if you know of a way to navigate the force directed diagram either by mouse wheel scrolling and clicking to pan or using the keyboard. Any help is appreciated.

networkSeries.maxLevels = 1; is the only thing I could think of as I did not come across anything that lets you navigate or pan force-directed graphs.maxLevels will reduce the space occupied but it still doesn't answer the question

Related

How can I scroll a Sheild UI chart horizontally at a time based speed

I was wondering if anyone can offer any advise/examples of using Shield UI charts to show a horizontally scrolling graph over a time period.
I am open to suggestions about how to achieve this but would like to see real-time (per second or less accuracy) scrolling, either by frequent updating of a single graph or perhaps better, simply moving a vertical line marker from left to right across the y-axis to demonstrate the movement of time, relative to a static background chart.
May you specify some more details about what you want to achieve as it is not quite clear? Can you give some image/example how it should look like?
I think you should look at that demo, probably it is something near to what you have asked.
http://demos.shieldui.com/web/line-chart/forex-data
There as you can see you can dynamically rebind chart and simulate live data. Scrolling starts after it is filled with data. Probably that is something similar to what you want to achieve.

D3.js scattergraph with large (>500,000) points? Clustering?

I'm looking at plotting a scatterplot with a large number of points (500,000 and upwards).
Currently, we're doing this in Python with Matplotlib. It plots the points, and it provides controls to pan and zoom. I don't believe it provides any clustering or points, it just plots them all - doesn't make much sense at the zoomed out view, I suppose, but you can zoom in and they're all there.
I was looking at doing the chart in JavaScript, to make it a bit easier to distribute. I was looking at D3.js, to see if something similar is feasible there. I did find this example of a basic scatterplot:
http://bl.ocks.org/mbostock/3887118
Firstly, would you be able to plot that number of points? (500,000 and upwards) I was under the impression you couldn't due to the overhead of all the DOM objects? Are there ways around this?
Secondly, is there any kind of clustering available, either a library or even just an example of this being done in D3.js?
Thirdly, if anybody knows any good examples of pan/zoom functionality and clustering, or even just a packaged JS library that handles it, that would be awesome.
Fourth, it would be also nice to have click handlers for each point - and to display some text either in a overlay, or even just in a separate window. Any thoughts on this?
Can you draw half a million points with D3? Sure, but not with SVG. You'll have to use canvas (here's a simple example with 10,000 points that includes brush-based selection: http://bl.ocks.org/emeeks/306e64e0d687a4374bcd) and that means that you no longer have individual elements to assign click handlers to. You will not be able to render half a million points with SVG, because all those DOM elements will choke your interface, as you mentioned.
D3 does include quadtree support that can be leveraged for clustering. It's in use in the above example to speed up search but you could use it to nest elements in proximity at certain scales.
Ultimately, your choices are:
1) Some other library/custom implementation that renders in canvas and polls the mouse position to give you the data element rendered at that point.
2) A sophisticated custom D3 approach that nests elements in proximity and only renders SVG elements appropriate at the zoom level and canvas position (pan) you're at.
Yes, D3.js can be made to work with million scale data with two things:
pre-rendering on the server side. For more see here: https://mango-is.com/blog/engineering/pre-render-d3-js-charts-at-server-side/
By aggregating (or clustering) part of the data so that user can interact and expand the graph if need be. For this use collapsible nodes if you can (http://bl.ocks.org/mbostock/1062288).
Also avoid using force layout. It takes time to settle and converge to a stable positioning.
For clustering libraries, I would pick one up off the shelf. I would choose the scikits library from python, there are many in JavaScript but they are not very robust as they mostly cover k-means or hierarchical clustering. I would precalculate the coordinates using scikits by clustering and then render it using D3.
D3 handles Pan and zoom. Again click handlers and text display are available in D3. (http://bl.ocks.org/robschmuecker/7880033)

Prevent node overlap in force directed graph

I have build a force directed graph for the social network analysis.
The problem which I am facing is that nodes keeps on overlapping each other,
How can I prevent overlapping of node in force directed graph ?
Here is my code with dummy data
And following is the image for my force directed graph
How can I remove overlapping of these nodes ? and how can I keep atleast some distance between links so that links are properly visible ?
There are two approaches to avoiding overlap in a d3 force layout.
The first is to adjust the parameters of the force object, the most relevant of which is the "charge" parameter. Nodes with negative "charge" values push other nodes away (versus nodes with positive values pull other nodes closer), and you can increase the amount of charge to cause a greater push.
The default value for the "charge" is -30, so from there you can adjust it until you get an effect you want. There's no simple formula for determining the value you want, since it also depends on the other parameters and the amount of links in your graph.
If for any reason adjusting the charge doesn't work for you (for example, if you want the nodes to cluster close to each other -- not repel each other -- but still not overlap), then you can manually check for overlapping nodes, as in this Mike Bostock example suggested by Josh in the comments.

d3: Make a static directed graph

I'd like to visualize a 20K node dependency graph in d3. Force-directed graphs such as http://bl.ocks.org/mbostock/1153292 are too slow to render in the browser for this number of nodes.
Basically I want to represent nodes containing text and directed edges from one node to another, and add zooming and panning functionality. How can I go about doing this in d3?
Here's an alternative which doesn't seem to use force to lay out the nodes - there's no springing, performs well, and has built in upload/download facility. Its license is MIT/X:
Interactive tool for creating directed graphs using d3.js
directed-graph-creator
Operation:
drag/scroll to translate/zoom the graph
shift-click on graph to create a node
shift-click on a node and then drag to another node to connect them with a directed edge
shift-click on a node to change its title
click on node or edge and press backspace/delete to delete
The zoom behaviour (and pan) you would get basically for free through the zoom behaviour. The layout you would have to do yourself though -- the force layout is pretty much the only thing in D3 you can use to lay out a graph of this kind.
Regardless of what you're using, with 20K nodes anything dynamic is going to be pretty slow -- simply rendering all the elements is going to take quite some time during which the browser will seem unresponsive. An alternative you may want to consider is to pre-render the graph using something more suitable for large amounts of data, save the result as an image (or even static SVG) and add a little bit of D3 code on top for zoom/pan.

D3.js Force Layout - showing only part of a graph

Good morning,
just starting with the awesome d3js library ...
I want to show only a portion of a graph with the force directed layout. The idea is to have one node declared as the "center" and show all nodes within a distance of two (for example) from this center node, the neighbors of the center node and the neighbors of the neighbors. If the user clicks on one of the displayed nodes it becomes the "new" center node and a different "subgraph" is displayed. I wonder if there is an example around implementing this kind of subgraph layout and if some kind of a "node-distance" algorithm is already implemented in d3js.
Thanks a lot
martin
UPDATE:
Just found the example Modifying a Force Layout which illuminates how to add and remove nodes and edges from a force directed layout.
I just uploaded a "proof of concept level" of an interactive force directed subgraph.
http://justdharma.com/d3/sub-graph/
In this example I use backbonejs under the hood. Being the first time I implement something with backbonejs, I for sure use it in a very crude manner. While this example might illuminate one way how an interactive sub-graph can be achieved it is for sure not a template how to do it - as said just a proof of concept hack ...
This isn't implemented in D3, and I'm not aware of any examples. What you would have to do is the following:
Set the fixed attribute of the new center node to true to prevent the force layout from changing its position.
Set the px and py attributes of that same node to the center position.
For each node in your force layout, compute the shortest path to the new center node.
Depending on the length of the path in each case, either remove the node or keep it.
The trickiest part here is the computation of the path from each node to the new center, but even this is a pretty standard algorithmic problem. Another thing to keep in mind is that you need to modify the data structures that contain the nodes and links of the force layout in place, i.e. you can't set new nodes and links for the force layout and expect everything to work smoothly.

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