I'm writing MapBox vector tiles using geotrellis vectorpipe.
see here for the basic flow: https://geotrellis.github.io/vectorpipe/usage.html
Typically GeoJson Features can have an id field, so that Features can be rolled up into FeatureCollections. I need to make use of this field, but vectorpipe doesn't (natively) have this capability.
This is the Feature type used, and you can see it only has space for 1) a Geometry and 2) a data object D (which ends up populating properties in the output). There is no spot for an id.
https://geotrellis.github.io/scaladocs/latest/index.html#geotrellis.vector.Feature
Upstream there's a method called writeFeatureJsonWithID() that does let you inject an id field into a Feature when writing GeoJson.
https://github.com/locationtech/geotrellis/blob/master/vector/src/main/scala/geotrellis/vector/io/json/FeatureFormats.scala#L41-L49
My question is this:
I have worked through the vectorpipe code (https://github.com/geotrellis/vectorpipe), and I can't figure out if/where the data ever exists as GeoJson in a way where I can override and inject the id, maybe using the writeFeatureJsonWithID() or something I write explicitly. A lot of conversions are implicit, but it also may never explicitly sit as json.
Any ideas for how to get an id field in the final GeoJson written to vector tiles?
EDIT
Right now I think the trick is going to be finding a way to override .unfeature() method here:
https://github.com/locationtech/geotrellis/blob/master/vectortile/src/main/scala/geotrellis/vectortile/Layer.scala
The problem is that the internal.vector_tile.Tile is private, so I can construct it without forking the project.
Ended up having to fork geotrellis, hard-code a metadata => id function in Layer.unfeature() and compile locally to include in my project. Not ideal, but it works fine.
Also opened an issue here: https://github.com/locationtech/geotrellis/issues/2884
Related
The vscode-antlr4 plugin for VisualStudio Code has a nice call-graph feature which visualizes (as a dendrogram) how grammar (and lexer) rules interact. You can save the graphic as SVG.
Is there a way to export the information as JSON? I wouldn't mind going into the plugin's code to find a way to do it.
My aim is to create reachability graphs for individual rules, i.e. graphs that show from which other rules a particular rule can be reached (transitively). The "calls" and "is-called" information from the call-graph feature would be a nice starting point.
The data for the call graph comes from a source context instance (for each grammar file there's a single source context to manage all details for it). See the function getReferenceGraph, which collects the relations into a map object. You can use that object to generate a JSON object from it. Or you create another function, taking this one as template, to generate the JSON directly, without the overhead required for the UI.
I noticed that hyperHTML preserves references I make to elements:
let div = document.createElement("div");
div.textContent = "Before Update";
hyperHTML.bind(document.body)`static1 - ${div} - static2`;
div.textContent = "After Update";
Above will produce a page that says:
static1 - After Update - static2
It is my understanding that hyperHTML ultimately clones an HTML <tempate> element to render the final output. However, don't you typical lose references when cloning an HTML template (like the variable "div" in the example above)?
Therefore, on the initial render, does hyperHTML somehow replace cloned elements with their originals after cloning the HTML template?
Here's how I think it works:
Create an HTML Template of the original template literal while
replacing all interpolations with comments.
Clone the html template with comments left in.
Make elements or document fragments out of each interpolation originally recieved
Replace each comment in the clone with its processed interpolation.
Is this correct?
I am not sure what is the question here, but there is a documentation page, and various examples too to understand how to use hyperHTML, which is not exactly in the way you are using it.
In fact, there's no need to have any reference there because hyperHTML is declarative, so you'd rather write:
function update(text) {
var render = hyperHTML.bind(document.body);
render`static1 - <div>${text}</div> - static2`;
}
and call update("any text") any time you need.
Here's how I think it works ... Is this correct?
No, it's not. hyperHTML doesn't clone anything the way you described, it associates once per unique template tag a sanitized version to the output and finds out all interpolated holes in it.
The part of the library that does this is called domtagger, and the mapping per template literal is based on the standard fact that these are unique per scope:
const templates = [];
function addTemplate(template, value) {
templates.push(template);
return template.join(value);
}
function asTemplate(value) {
return addTemplate`number ${value}!`;
}
asTemplate(1);
asTemplate(2);
asTemplate(Math.random());
templates[0] === templates[1]; // true
templates[1] === templates[2]; // true
// it is always the same template object!
After that, any other element using once that very same tag template will have a clone of that fragment with a map to find holes once and some complex logic to avoid replacing anything that's already known, being that text, attributes, events, or any other kind of node.
hyperHTML never removes comments, it uses these as pin and then uses domdiff to eventually update nodes related to these pins whenever there's a need to update anything.
Domdiff is a vDOM-less implementation of the petit-dom algorithm, which in turns is based on E.W Myers' "An O(ND) Difference Algorithm and Its Variations" paper.
Whenever you have DOM nodes in the holes, hyperHTML understand that and fill these holes with those nodes. If you pass repeatedly the same node, hyperHTML won't do anything 'cause it's full of algorithm and smart decisions, all described in the documentation, to obtain best performance out of its abstraction.
All these things, and much more, normalized for any browser out there, makes hyperHTML weight roughly 7K once minified and gzipped, bit it also offers:
Custom Elements like hooks through onconnected/disconnected listeners
lightweight components through hyperHTML.Component
SVG manipulation as content or via wire
easy Custom Elements definition through HyperHTMLElement class
As summary, if you need these simplifications and you don't want to reinvent the wheel, I suggest you give it a better try.
If you instead are just trying to understand how it works, there's no need to assume anything because the project is fully open source.
So far, all I've read from your questions here and there, is that you just believe to understand how it works so I hope in this reply I've put together all the missing pieces you need to fully understand it.
Do you want to write your own lit/hyperHTML library? Go ahead, feel free to use the domtagger or the domdiff library too, few others are already doing the same.
I have a need to go through a set of DICOM files and modify certain tags to be current with the data maintained in the database of an external system. I am looking to use GDCM. I am new to GDCM. A search through stack overflow posts demonstrates that the anonymizer class can be used to change tag values.
Generating a simple CT DICOM image using GDCM
My question is if this is the best use of the GDCM API or if there is a better approach for changing the values of individual tags such as patient name or accession number. I am unfamiliar with all of the API options but have a link to the API documentation. It looks like the DataElement SetValue member could be used, but it doesn't appear that there is a valid constructor for doing this in the Value class. Any assistance would appreciated. This is my current approach:
Anonymizer anon = new Anonymizer();
anon.SetFile(myFile);
anon.Replace(new Tag(0x0010, 0x0010), "BUGS^BUNNY");
Quite late, but maybe it would be still useful. You have not mention if you write in C++ or C#, but I assume the latter, as you do not use pointers. Generally, your approach is correct (unless you use System.IO.File instead of gdcm.File). The value (second parameter of Replace function) has to be a plain string so no special constructor is needed. You should probably start with doxygen documentation of gdcm, and there is especially one complete example. It is in C++, but there should be no problems with translation.
There are two different ways to pad dicom tags:
Anonymizer
gdcm::Anonymizer anon;
anon.SetFile(file);
anon.Replace(gdcm::Tag(0x0002, 0x0013), "Implementation Version Name");
//Implementation Version Name
DatsElement
gdcm::Attribute<0x0018, 0x0088> ss;
ss.SetValue(10.0);
ds.Insert(ss.GetAsDataElement());
From the diagram on page 570 of the UML spec I concluded that a Lifeline should have the events property, holding an OrderedSet(OcurrenceSpecification). Unfortunately it is not there, at least in the QVTo implementation that I use.
All I have is the coveredBy property, serving me with an (unordered) Set(InteractionFragment). Since my transformation relies on the correct order of MessageOcurrenceSpecification I somehow need to implement myself what I expected to be implemented by the missing events property.
This is what I have so far:
helper Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.coveredBy->selectByKind(OccurrenceSpecification)->sortedBy(true);
}
Obviously sortedBy(true) does not get me far, but I don't know any further. Who can help?
All I could find so far were other people struggling with the same issue years ago, but no solution:
https://www.eclipse.org/forums/index.php/m/1049555/
https://www.eclipse.org/forums/index.php/m/1050025/
https://www.eclipse.org/forums/index.php/m/1095764/
Based on the answer by Vincent combined with input from a colleague of mine I came up with the following solution for QVTo:
-- -----------------------------------------------------------------------------
-- Polyfill for the missing Lifeline::events property
query Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.interaction.fragment
->selectByKind(OccurrenceSpecification)
->select(os: OccurrenceSpecification | os.covered->includes(self))
->asOrderedSet();
}
I don't know if it is possible, using directly coveredBy to get an ordered collection. As coveredBy is unordered, if you access it directly by the feature, you will have an unpredictible order and if you try to access it using the eGet(...) stuff, the same result will occur.
However, if I understood correctly, there is a "trick" that could work.
It relies on the assumption that each OccurrenceSpecification instance you need is held by the same Interaction that contains the Lifeline and uses the way EMF stores contained elements. Actually, each contained element is always kind of 'ordered' relatively to its parent (and for each collection so EMF can find elements back when XMI references are expressed using the element position in collections). So, the idea would be to access all the elements contained by the Interaction that owns the lifeline and filter the ones that are contained in coveredBy.
Expression with Acceleo
This is easy to write in MTL/Acceleo. In know you don't use it, but it illustrates what the expression does:
# In Acceleo:
# 'self' is the lifeline instance
self.interaction.eAllContents(OccurrenceSpecification)->select(e | self.coveredBy->includes(e))->asOrderedSet()
with self.interaction we retrieve the Interaction, then we get all the contained elements with eAllContents(...) and we filter the ones that are in the self.coveredBy collection.
But it is way less intuitive in QVT as eAllContents(...) does not exist. Instead you have to gain access to eContents() which is defined on EObject and returns an EList which is transtyped to a Sequence (in QVT,eAllContents() returns a ETreeIterator which is not transtyped by the QVT engine).
So, how to gain access to eContents() in the helper? There is two solutions:
Solution 1: Using the emf.tools library
The emf.tools library give you the ability to use asEObject() which casts your object in a pure EObject and give you more methods to access to (as eClass() for example...etc).
import emf.tools; -- we import the EMF tools library
modeltype UML ...; -- all your metamodel imports and stuffs
...
helper Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.interaction.asEObject().eContents()[OccurrenceSpecification]->select(e | self.coveredBy->includes(e))->asOrderedSet();
}
Solution 2: Using oclAstype(...)
If for some reason emf.tools cannot be accessed, you can still cast to an EObject using oclAsType(...).
modeltype UML ...; -- all your metamodel imports and stuffs
modeltype ECORE "strict" uses ecore('http://www.eclipse.org/emf/2002/Ecore'); -- you also register the Ecore metamodel
...
helper Lifeline::getEvents (): OrderedSet(OccurrenceSpecification) {
return self.interaction.oclAsType(EObject).eContents()[OccurrenceSpecification]->select(e | self.coveredBy->includes(e))->asOrderedSet();
}
Limitation
Ok, let's be honest here, this solution seems to work on the quick tests I performed, but I'm not a 100% sure that you will have all the elements you want as this code relies on the strong assumption that every OccurrenceSpecification you need are in the same Interaction as the Liteline instance. If you are sure that all the coveredBy elements you need are in the Interaction (I think they should be), then, that's not the sexiest solution, but it should do the work.
EDIT>
The solution proposed by hielsnoppe is more eleguant than the one I presented here and should be prefered.
You are correct. The Lifeline::events property is clearly shown on the diagram and appears in derived models such as UML.merged.uml.
Unfortunately Eclipse QVTo uses the Ecore projection of the UML metamodel to UML.ecore where unnavigable opposites are pruned. (A recent UML2Ecore enhancement allows the name to be persisted as an EAnnotation.) However once the true property name "events" has been pruned the implicit property name "OccurrenceSpecification" should work.
All associations are navigable in both directions in OCL, so this loss is a bug. (The new Pivot-based Eclipse OCL goes back to the primary UML model in order to avoid UML2Ecore losses. Once Eclipse QVTo migrates to the Pivot OCL you should see the behavior you expected.)
I don't quite understand how to use application specific YAML tags, and maybe its because my desired use of them is purely wrong. I am using YAML for a configuration file and was hoping to use tags to provide my configuration loader with a hint as to what datatype it should parse the data into - application specific datatypes.
I'm also using libyaml with C.
So I'm trying to do something like...
shapes:
square: "0,4,8,16"
circle: "5,10"
In my app I'd like to use tags as hints so I can load the values of square into my square data structure, and the values of circle into my circle data structure (these values mean nothing in this example).
So I'm currently doing:
shapes:
square: !square "0,4,8,16"
circle: !circle "5,10"
Libyaml will provide a tag of "!square" when I'm passed the scalar "0,4,8,16". Is it valid to use this tag to provide my loader with a hint of how to process the scalar?
Since it does work for me, I'm more curious to know if its proper. And if not, how would I go about making this more proper.
Thanks.
I know that this is an ancient question, but anyway I've seen !int, etc being used in yaml files before so I went to look up the specs at Yaml 1.2 Spec # Tags
application specific tag: !something |
The semantics of the tag
above may be different for
different documents.
As per the document, it does look like your intended usage of tags is correct for application specific tag.