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Questions tagged [projection]

A projection is the transformation of a set of data from one form into another.

Mathematically speaking a projection is a function that yields the same result if applied multiple times.

The term is used with this meaning in graphics when 'projecting' a 3D scene on a 2D canvas.

The same is often happening when analyzing data with many dimensions (age, gender, number of transactions, ...) and projecting it on fewer dimensions, in the simple case by just dropping dimensions or by creating new dimensions like (might commit fraud).

When dealing with typed languages the dimensions might be attributes of a class. So if I have one or multiple types with attributes (A, B, C, ...) and create from instances of those types instances of a type which has only the attributes (A, B) this is a projection too.

Another example are databases. A projection is an operation which discards some attributes of a tuple, in other words, which omits some columns of a relational database query result. For an object or document database a projection filters out some fields.

After all a database projection yields the same result if applied multiple times, too.

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Raster extent is no longer correct after using projectRaster in R

I have one elevation raster and one set of data points that I would like to be in the same projected coordinate system. When I use projectRaster, the extent of the layer becomes completely different and no longer lines up with the other data…
fin
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Querying EventStoreDB with java API or HTTP API

I have been using the brilliant Event Store DB by brilliant Greg Young lately and its fine. But the documentation is awful, it's outdated, sometimes incorrect, and distributed through the website. Sometimes you have to lookup multiple non relevant…
Masoudy BaBa
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OpenCV: Get transformation matrix without camera calibration

I am building a React Native app that uses OpenCV under the hood. What I want to do is project an image over the phone's camera feed onto a frame. I have the four points to calculate cv::getPerspectiveTransform with and could simply do a…
MrGVSV
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raster does not align with shapefile after processing with rgee

I defined a polygon: library(rgee) ee_Initialize() polygon <- ee$Geometry$Polygon( list( c(91.17, -13.42), c(154.10, -13.42), c(154.10, 21.27), c(91.17, 21.27), c(91.17, -13.42) )) Map$addLayer(polygon) The polygon…
89_Simple
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Mongo export query to project only specific field in the json object within json array

I have a requirement to project only specific field in the json object within json array. Let's say I have a collection with many documents like below { "_id" : Object("sddf3r"), "item_id" : "1235", "outerObj" : [{ "fieldA" : "valueA", …
Aarish Ramesh
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Mongodb projection-->differents property on localhost and production deploy

i develop an app on react on MERN Stack.Server side setup i've created a controller and i've defined a projection in order to spécify the property to send in a json. it works on local with postman . but when i deploy my app, the result of api call…
tzakrzewski-dev
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Failing to assign projection to sp object SpatialPointsDataFrame

I have a SpatialPointsDataFrame called johnny, created from a vanilla dataframe by assigning coordinates. These coordinates are in coordinate system EPSG 4326 (the standard GPS geographic coordinate system), but johnny does not know that. So ,I am…
Albert Heim
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how to remove _id from create replay mongodb node js

exports.createDD_PR_addresstype = asyncHandler(async (req, res, next) => { const dropdowns = await DD_PR_addresstype.create(req.body); res.status(200).json({ success: true, data: dropdowns }); }); replay { "success": true, …
Santhosh
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Render Simple 3D object (vectors) and then create 2D transformations (rotations) of that object

I need to create a fairly simply 3D space ship object which would really be comprised of about 3 dozen vectors (maybe a dozen planes). I have no need for surface rendering or lighting, simply plane-edge vectors. Once I have the 3D vector model of…
jaskey
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Can this stock graph be made using Highstock?

Could this graph be made using Highstock? I'm currently using Highstock, but never saw this kind. Before I waste weeks trying, the question needs to be asked... If yes, how can this be made? by shifting the stock chart, and create another Xaxis at…
FrancoisG
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How do you use column projection in a Mongoose collection.find query? The documented method does not work

The following query returns all non-command queries in the profile table of my DB. I tried to ask it not include the command column using what the Mongoose documentation suggests and my returned object still has the command column. I also tried "op…
kamii
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Reporting integration composition

I have an architecture based on several Self-Contained Systems (Microservices, if you want), each one of them owning a given set of data. We would like to implement a reporting database (with near-realtime updates) by integrating all of the systems…
Stefano
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How to loop over the values of a field during MongoDB project?

Question: What I want is to loop over on the values of a field during the Mongo project, For Example: Here is a small sample of my data { "_id": ObjectId(1), "field1": { "key1":"value1", "key2":"value2" } }, { "_id": ObjectId(1), "field1": { …
Phoenix
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importing shapefile to geopandas using read_file(); can't print crs or reproject

I have a shapefile of historical county boundaries with a valid .prj file. I can open it in ArcGIS and find that the projection is USA Contiguous Albers Equal Area Conic. I can also plot the shapefile after I have read it into geopandas and the…
user2905280
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Projection of 2D histogram to one axis with matplotlib

I have the following code where I produced a 2d histogram with matplotlib of a function f of two variables, namely x and y. x goes from 0 to 7 and y from 0 to np.pi/2. Below you can find related code. I would like to project onto the x-axis so that…
Stefano555
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