Red-black tree is a kind of AVL tree which is widely used in data base for it is efficient in CRUD. Why react do not use it as its virtual DOM tree model? You'd better give me a mathematic proof.
I guess there is a reason that AVL tree is to make searching more quickly, but in UI area, we often concentrate on tree's diff and transform. But another question, is there a kind of data structure can make tree diff and transform more efficient?
Related
Quite new with d3 but have been stuck on this for several weeks and figured I'd ask here
I've been trying to create a radial/flare tree using React-Flow but I'm having a really hard time with positioning the nodes. I need to use React-Flow because I'd like to use custom React components instead of the standard SVG nodes from d3 since I need a higher fidelity interaction with the nodes.
Essentially I'm looking for something like this attached image but using React-Flow:
Source: https://observablehq.com/#d3/radial-tree
I don't even need the radial curve lines- it's more of a nice to have. As long as I can get the nodes in the correct circular position, even straight lines are fine.
Would love any advice :)
Here's what I've got so far:
https://codesandbox.io/s/trusting-leavitt-b8uxi9-rf-expand-collapse-forked-fh71v8?file=/src/App.tsx:948-954
It's the collapsible tree example that the React-Flow devs gave on their website
The closest example of a radial tree using d3 using v4 or above is this: https://medium.com/analytics-vidhya/creating-a-radial-tree-using-d3-js-for-javascript-be943e23b74e
I'm trying to apply the logic that the author used in their example but the nodes aren't positioning correctly, probably due to my shallow understanding of how to use d3
There are a few other examples on here/codepen that creates a radial tree using d3 but they're all v3 or below and are focused around using SVGs as the nodes
I've also seen other radial trees from other React libraries like this: https://codesandbox.io/s/ov2jokvl1z
But they all use SVG nodes which won't work for me because I'd like to use React nodes within the graph
I need to associate SceneKit Node objects with arbitrary objects in my program and am looking for an optimal solution.
Here is an example of what I mean:
Say I have a program that renders atoms in a molecule using SceneKit. I have classes Molecule and Atom that model my data. I then render the molecule using SceneKit.
When I click on a sphere node in the Scene View, I need to know which Atom object that sphere represents (the Molecule contains an array of Atoms)
I could create a Dictionary that maps Node to Atom object, but wonder if there is a way to add an Atom object reference to the sphere node. Should one use Key-Value bindings?
I am very new to Cocoa programming and am looking for a nudge in the right direction for an approach. I can then research the implementation specifics.
How about starting with a couple of different SCNNode subclasses? The first is for your Atom, the second for your Molecule. Each MoleculeNode has one or more AtomNodes as children. AtomNode and MoleculeNode have weak references back to the Atom or Molecule they represent.
Now you can move or rotate a MoleculeNode easily, and all of the AtomNodes will move with it. Each AtomNode's geometry will stay fixed, relative to the parent MoleculeNode.
Hit testing will return both AtomNodes and MoleculeNodes. You can filter that result if you want, by either the node's class, or by setting the node's name to "Atom" or "Molecule". The SCNHitTestBoundingBoxOnlyKey might be useful if you want to be lenient about the precision of clicks required.
Just as a small alternative you can you a Map from SCNNode to ModelObject.
I'm new to x3d/vrml and I'm trying figure out how to punch a hole in a solid shape. For example, a 6x6x2 cube with a smaller 2x2x2 cube in the middle to create a hollow shape. I have tried extrusion and indexedFaceSet without success. I haven't found any tutorials that show me how to do this. Therefore, A working example would be useful to me as well as others .
Normally you don't create this kind of shapes manually. Of course it is possible to use the IndexedFaceSet node in order to achieve this but it's much better and easier to use a tool (e.g. 3D Studio Max) where you can create shapes using a graphical interface. Then you export the file to X3D or VRML or whatever and you'll see the IndexedFaceSet there and possibly the complexity of the node (I mean the node values which are nearly impossible to determine by yourself).
In your specific case you could use 4 cubes that are intersecting and leaving a hole in the middle...this would be just a tricky solution.
According to my book, coloring red links that go from nodes of even height to nodes of odd height in an AVL tree gives a (perfectly balanced) 2-3-4 tree, where red links are not necessarily left-leaning.
But I don't get how exactly. When I try it with some examples, I keep getting stuck. Can someone illustrate it for me please?
In my web application I work with ExtJS4 and I use an Ext.tree.Panel. For a custom drag and drop implementation I need to find the tree node by its screen coordinates.
Is there a way to find a tree node by its screen coordinate? Or is it possible to find it via its HTML element?
Thanx in advance...
It would be not very efficient to seek node by coordinates as the only way to find the node by coordinates is to walk over all nodes.
Finding node by HTML element seems like more logical approach to me. Extjs4 tree utilizes the view. So you can try the view.getRecord method:
var node = tree.view.getRecord(htmlEl);
I haven't tried this code but it should work provided you passed correct htmlEl.
One part of your question has already been answered.
If you really need to get HTML element (use it only as last resort) by screen coordinates, then you will need document.elementFromPoint.
Extra info and quirks here: http://www.quirksmode.org/blog/archives/2010/06/more_ie9_goodne.html