76 lines
2.8 KiB
Markdown
76 lines
2.8 KiB
Markdown
# @turf/nearest-point-on-line
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<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
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## nearestPointOnLine
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Returns the nearest point on a line to a given point.
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### Parameters
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* `lines` **([Geometry][1] | [Feature][2]<([LineString][3] | [MultiLineString][4])>)** lines to snap to
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* `pt` **([Geometry][1] | [Feature][2]<[Point][5]> | [Array][6]<[number][7]>)** point to snap from
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* `options` **[Object][8]** Optional parameters (optional, default `{}`)
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* `options.units` **[string][9]** can be degrees, radians, miles, or kilometers (optional, default `'kilometers'`)
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### Examples
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```javascript
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var line = turf.lineString([
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[-77.031669, 38.878605],
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[-77.029609, 38.881946],
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[-77.020339, 38.884084],
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[-77.025661, 38.885821],
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[-77.021884, 38.889563],
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[-77.019824, 38.892368]
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]);
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var pt = turf.point([-77.037076, 38.884017]);
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var snapped = turf.nearestPointOnLine(line, pt, {units: 'miles'});
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//addToMap
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var addToMap = [line, pt, snapped];
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snapped.properties['marker-color'] = '#00f';
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```
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Returns **[Feature][2]<[Point][5]>** closest point on the `line` to `point`. The properties object will contain four values: `index`: closest point was found on nth line part, `multiFeatureIndex`: closest point was found on the nth line of the `MultiLineString`, `dist`: distance between pt and the closest point, `location`: distance along the line between start and the closest point.
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[1]: https://tools.ietf.org/html/rfc7946#section-3.1
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[2]: https://tools.ietf.org/html/rfc7946#section-3.2
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[3]: https://tools.ietf.org/html/rfc7946#section-3.1.4
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[4]: https://tools.ietf.org/html/rfc7946#section-3.1.5
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[5]: https://tools.ietf.org/html/rfc7946#section-3.1.2
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[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
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[7]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
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[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
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[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
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<!-- This file is automatically generated. Please don't edit it directly. If you find an error, edit the source file of the module in question (likely index.js or index.ts), and re-run "yarn docs" from the root of the turf project. -->
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---
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This module is part of the [Turfjs project](https://turfjs.org/), an open source module collection dedicated to geographic algorithms. It is maintained in the [Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create PRs and issues.
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### Installation
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Install this single module individually:
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```sh
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$ npm install @turf/nearest-point-on-line
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```
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Or install the all-encompassing @turf/turf module that includes all modules as functions:
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```sh
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$ npm install @turf/turf
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```
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