StackGenVis: Alignment of Data, Algorithms, and Models for Stacking Ensemble Learning Using Performance Metrics
https://doi.org/10.1109/TVCG.2020.3030352
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92 lines
3.8 KiB
92 lines
3.8 KiB
## geojson-vt — GeoJSON Vector Tiles
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[](https://travis-ci.org/mapbox/geojson-vt)
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[](https://coveralls.io/r/mapbox/geojson-vt)
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A highly efficient JavaScript library for **slicing GeoJSON data into vector tiles on the fly**,
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primarily designed to enable rendering and interacting with large geospatial datasets
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on the browser side (without a server).
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Created to power GeoJSON in [Mapbox GL JS](https://github.com/mapbox/mapbox-gl-js),
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but can be useful in other visualization platforms
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like [Leaflet](https://github.com/Leaflet/Leaflet) and [d3](https://github.com/mbostock/d3),
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as well as Node.js server applications.
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Resulting tiles conform to the JSON equivalent
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of the [vector tile specification](https://github.com/mapbox/vector-tile-spec/).
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To make data rendering and interaction fast, the tiles are simplified,
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retaining the minimum level of detail appropriate for each zoom level
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(simplifying shapes, filtering out tiny polygons and polylines).
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Read more on how the library works [on the Mapbox blog](https://www.mapbox.com/blog/introducing-geojson-vt/).
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There's a C++11 port: [geojson-vt-cpp](https://github.com/mapbox/geojson-vt-cpp)
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### Demo
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Here's **geojson-vt** action in [Mapbox GL JS](https://github.com/mapbox/mapbox-gl-js),
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dynamically loading a 100Mb US zip codes GeoJSON with 5.4 million points:
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There's a convenient [debug page](http://mapbox.github.io/geojson-vt/debug/) to test out **geojson-vt** on different data.
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Just drag any GeoJSON on the page, watching the console.
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### Usage
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```js
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// build an initial index of tiles
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var tileIndex = geojsonvt(geoJSON);
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// request a particular tile
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var features = tileIndex.getTile(z, x, y).features;
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// show an array of tile coordinates created so far
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console.log(tileIndex.tileCoords); // [{z: 0, x: 0, y: 0}, ...]
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```
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### Options
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You can fine-tune the results with an options object,
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although the defaults are sensible and work well for most use cases.
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```js
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var tileIndex = geojsonvt(data, {
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maxZoom: 14, // max zoom to preserve detail on; can't be higher than 24
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tolerance: 3, // simplification tolerance (higher means simpler)
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extent: 4096, // tile extent (both width and height)
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buffer: 64, // tile buffer on each side
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debug: 0, // logging level (0 to disable, 1 or 2)
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lineMetrics: false, // whether to enable line metrics tracking for LineString/MultiLineString features
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promoteId: null, // name of a feature property to promote to feature.id. Cannot be used with `generateId`
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generateId: false, // whether to generate feature ids. Cannot be used with `promoteId`
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indexMaxZoom: 5, // max zoom in the initial tile index
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indexMaxPoints: 100000 // max number of points per tile in the index
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});
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```
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By default, tiles at zoom levels above `indexMaxZoom` are generated on the fly, but you can pre-generate all possible tiles for `data` by setting `indexMaxZoom` and `maxZoom` to the same value, setting `indexMaxPoints` to `0`, and then accessing the resulting tile coordinates from the `tileCoords` property of `tileIndex`.
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The `promoteId` and `generateId` options ignore existing `id` values on the feature objects.
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GeoJSON-VT only operates on zoom levels up to 24.
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### Install
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Install using NPM (`npm install geojson-vt`) or Yarn (`yarn add geojson-vt`), then:
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```js
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// import as a ES module
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import geojsonvt from 'geojson-vt';
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// or require in Node / Browserify
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const geojsonvt = require('geojson-vt');
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```
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Or use a browser build directly:
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```html
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<script src="https://unpkg.com/geojson-vt@3.2.0/geojson-vt.js"></script>
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```
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