Cytoscape.js - not adding all "ele" at startup - cytoscape.js

Situation:
I have a graph with 500 nodes (say 1000 edges), with a root.
Goal:
I want the user able to progress in the graph, by cliking on nodes, showing the edges and new nodes around.
Way I do for now:
I first load all elements in memory (the entire json), then use ele.remove() for each nodes/edges. And just keep visible the root and around.
Question 1)
Is there any solution to choose the element to display at startup.(and not removing them later)
Question 3)
Removing the element does not free memory. Is there a solution to use memory for only elements that are not removed ?
Question 2)
Are there a smarter/better approach to do the trick ?
Thanks a lot

Using classes with visibility-related properties, as mentioned, would work.
You can also animate elements and animate the viewport to highlight parts of the graph.

Related

Vue displaying large matrix crashes browser

I am trying to display a large matrix that is constructed of 0/1, each cell is a div which could be black or white, when trying to display matrix of size 1000x1000 the browser crashes...
I am using v-for nested with v-for to display it...
how can i improve the performance?
This is not a Vue-related problem, but rather a DOM related problem. You are putting over a million DOM elements on a page. A tab where I ran a test that generated a stable 1000x1000 matrix with empty divs and classes showed that it consumed 2.3GB of memory. It took quite some time to even render, and scrolling is very slow, which suggests that it is the browser that is having trouble here. Vue does not do anything in my test after having rendered the page.
What you can do depends on the use case. If you just want to display data in a graphical way, consider using a canvas. You can freely draw on a canvas, and since you do not have to juggle around a million dom elements, the performance should be much better.
Other techniques include lazy loading, where you use scroll position to only load/show the rows that are in the viewport. This will reduce the number of dom elements, which should increase performance.
Alternatively you can limit the amount of data that is served to the user, by providing a filter or something similar. If a filter matches too many items, you can cut it off at a certain number of items you know will render fine in a browser and show a message that some of the results are hidden for performance reasons.

Dynamic/scrollable container size in Cytoscape (+ cy.fit() issues)

So I've been giving Cytoscape a try recently. My project's goal is basically a collaborative graph that people will be able to add/remove nodes to/from, making it grow in the process. The graph will include many compound nodes.
Most of the examples I've seen use container div that takes 100% of the screen space. This is fine for "controlled" graphs but won't work in my case because its size is intended to be dynamic.
Here's a JSFiddle using the circle layout within a fixed 3000px/3000px container:
https://jsfiddle.net/Jeto143/zj8ed82a/5/
Is there any way to have the container size be dynamic as opposed to stating it explicitly? Or do I have to compute the new optimal container size each time somehow, and then call cy.resize()?
edit: actually, using 100%/100% into cy.fit() might just work no matter how large the network is gonna be, so please ignore this question is this is the case.
Is there a recommended layout for displaying large/unknown amounts of data in a non-hierarchical way that would "smartly" place nodes (including compound ones) in the most efficient way possible, all the while avoiding any overlap? (I guess that's a lot to ask...)
Why doesn't cy.fit() seem to be working in my example? I'm using it both at graph initialization and when CTRL+clicking nodes (to show closed neighborhood), but it doesn't seem to like the 3000x3000px container (seems better with 100%x100%).
edit: also ignore this question if you ignored 1., as again it seems fine with 100%/100%.
Any help/suggestions would be greatly appreciated.
Thank you very much in advance.
TLDR: It's (1).
Cytoscape has a pannable viewport, like a map. You can define the dimensions of the viewport (div) in CSS. What's displayed in the viewport is a function of the positions of the nodes, the zoom level, and the pan level -- just like what is visible in a map's viewport is a function of zoom, pan, and positions of points of interest.
So either you have to
(a) rethink your UI in terms of zoom and pan and use those in-built facilities in Cytoscape, or
(b) disable zoom and pan in Cytoscape (probably stay at (0, 0) at zoom 1) and let the user scroll the page as you add content to the graph and resize its container div to accommodate the new content.

Kivy: Depth Oder not so in Depth

Now I could be wrong about this but after testing it all day, I have discovered...
When adding a widget and setting the z-index, the value "0" seems to be the magic depth.
If a widget's Z is at 0, it will be drawn on top of everything that's not at 0, Z wise.
It doesn't matter if a widget has a z-index of 99, -999, 10, -2 or what ever... It will not appear on top of a widget who's z-index is set to 0.
It gets more strange though...
Any index less than -2 or greater than 2 seems to create an "index out of range" error. Funny thing is...when I was working with a background and sprite widget, the background's Z was set to 999 and no errors. When I added another sprite widget, that's when the -2 to 2 z-index limitation appeared.
Yeah I know...sounds whacked!
My question is, am I right about "0" being the magic Z value?
If so, creating a simple 23D effect like making a sprite move being a big rock will take some unwanted code.
Since you can only set Z when adding,a widget, one must remove and immediately add back, with the new Z value...a widget.
You'll have to do this with the moving sprite and the overlapping object in question. Hell, I already have that code practically written but I want to find out from Kivy pros, is there a way to set z-index without removing and adding a widget.
If not, I'll have to settle for the painful way.
My version of Kivy is 1.9.0
What do you mean by z-order? Drawing order is determined entirely by order of widgets being added to the parent, and the index argument to add_widget is just a list index at which the widget will be inserted. The correct way to change drawing order amongs widgets is to remove and add them (actually you can mess with the canvases manually but this is the same thing just lower level, and not a better idea).
I found a working solution using basic logic based on the fact widgets have to be removed and added again in order to control depth/draw order.
I knew the Main Character widget had to be removed along with the object in question...so I created a Main Character Parent widget, which defines and control the Main Character, apart from its Graphic widget.
My test involves the Main Character walking in front of a large rock, then behind it...creating a 23D effect.
I simply used the "y-" theory along with widget attach and detach code to create the desired effect.
The only thing that caught me off guard was the fact my Graphic widget for my Actor was loading textures. That was a big no no because the fps died.
Simple fix, moved the texture loading to the Main Character Parent widget and the loading is done once for all-time.
PS, if anyone knows how to hide the scrollbars and wish to share that knowledge, it'll be much appreciated. I haven't looked for an API solution for it yet but I will soon.
Right now I'm just trying to make sure I can do the basic operations necessary for creating a commercial 23D game (handhelds).
I'm a graphic artist and web developer so coming up with lovely visuals won't be an issue. I'm more concerned with what'll be "under the hood" so to say. Hopefully enough, lol.

cytoscape.js redraw after hiding nodes

I'm using Cytoscape JS to create a network. This is a large network and I need to hide some nodes to be more readable, but I can't redraw my network not including the hiding nodes.
How can I redraw using auto-layout after hiding some nodes?
It's not clear to me exactly what you mean. An example would probably help. There are different semantics for hidden versus removed elements, and it sounds like perhaps you want the elements removed.
I ended up solving similar problem by just having two instances of Cytoscape.js on a page. First is headless one (invisible, with no HTML-representation) that stores all data I have. Second one is visible and has a subset of objects I want to be visible and layouted at the moment.
Copying elements between instances is extremely easy, like:
cy.add(datacy.$('#elem1'));

What's this kind of graph called?

I have a kind a graph, I found it while googling "tree graph" though it doesn't look like a normal tree-graph. So I was wondering, is it also just called a "tree-graph" or has it a more specific name? I want to look up more info about them, though can't really search for it without a proper name.
Thanks a lot!
PS. I'm not sure if this is the correct place to ask this, if it's not, please direct me to the proper place. Thanks.
Google calls it a Treemap and provides several examples and an ontology. They define the treemap as follows:
A visual representation of a data tree, where each node can have zero or more children, and one parent (except for the root, which has no parents). Each node is displayed as a rectangle, sized and colored according to values that you assign. Sizes and colors are valued relative to all other nodes in the graph.
Source: Google Developers / Google Charts
It's typically called a "heat map" or "heat chart".
That's a Treemap:
Treemaps display hierarchical (tree-structured) data as a set of
nested rectangles. Each branch of the tree is given a rectangle, which
is then tiled with smaller rectangles representing sub-branches. A
leaf node's rectangle has an area proportional to a specified
dimension on the data. Often the leaf nodes are colored to show a
separate dimension of the data.