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149 lines
3.9 KiB
Markdown
149 lines
3.9 KiB
Markdown
# normalize-range
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Utility for normalizing a numeric range, with a wrapping function useful for polar coordinates.
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[](https://travis-ci.org/jamestalmage/normalize-range)
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[](https://coveralls.io/github/jamestalmage/normalize-range?branch=master)
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[](https://codeclimate.com/github/jamestalmage/normalize-range)
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[](https://david-dm.org/jamestalmage/normalize-range)
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[](https://david-dm.org/jamestalmage/normalize-range#info=devDependencies)
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[](https://nodei.co/npm/normalize-range/)
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## Usage
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```js
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var nr = require('normalize-range');
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nr.wrap(0, 360, 400);
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//=> 40
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nr.wrap(0, 360, -90);
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//=> 270
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nr.limit(0, 100, 500);
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//=> 100
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nr.limit(0, 100, -20);
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//=> 0
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// There is a convenient currying function
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var wrapAngle = nr.curry(0, 360).wrap;
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var limitTo10 = nr.curry(0, 10).limit;
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wrapAngle(-30);
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//=> 330
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```
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## API
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### wrap(min, max, value)
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Normalizes a values that "wraps around". For example, in a polar coordinate system, 270˚ can also be
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represented as -90˚.
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For wrapping purposes we assume `max` is functionally equivalent to `min`, and that `wrap(max + 1) === wrap(min + 1)`.
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Wrap always assumes that `min` is *inclusive*, and `max` is *exclusive*.
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In other words, if `value === max` the function will wrap it, and return `min`, but `min` will not be wrapped.
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```js
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nr.wrap(0, 360, 0) === 0;
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nr.wrap(0, 360, 360) === 0;
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nr.wrap(0, 360, 361) === 1;
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nr.wrap(0, 360, -1) === 359;
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```
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You are not restricted to whole numbers, and ranges can be negative.
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```js
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var π = Math.PI;
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var radianRange = nr.curry(-π, π);
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redianRange.wrap(0) === 0;
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nr.wrap(π) === -π;
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nr.wrap(4 * π / 3) === -2 * π / 3;
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```
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### limit(min, max, value)
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Normalize the value by bringing it within the range.
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If `value` is greater than `max`, `max` will be returned.
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If `value` is less than `min`, `min` will be returned.
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Otherwise, `value` is returned unaltered.
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Both ends of this range are *inclusive*.
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### test(min, max, value, [minExclusive], [maxExclusive])
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Returns `true` if `value` is within the range, `false` otherwise.
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It defaults to `inclusive` on both ends of the range, but that can be
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changed by setting `minExclusive` and/or `maxExclusive` to a truthy value.
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### validate(min, max, value, [minExclusive], [maxExclusive])
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Returns `value` or throws an error if `value` is outside the specified range.
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### name(min, max, value, [minExclusive], [maxExclusive])
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Returns a string representing this range in
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[range notation](https://en.wikipedia.org/wiki/Interval_(mathematics)#Classification_of_intervals).
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### curry(min, max, [minExclusive], [maxExclusive])
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Convenience method for currying all method arguments except `value`.
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```js
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var angle = require('normalize-range').curry(-180, 180, false, true);
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angle.wrap(270)
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//=> -90
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angle.limit(200)
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//=> 180
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angle.test(0)
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//=> true
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angle.validate(300)
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//=> throws an Error
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angle.toString() // or angle.name()
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//=> "[-180,180)"
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```
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#### min
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*Required*
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Type: `number`
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The minimum value (inclusive) of the range.
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#### max
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*Required*
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Type: `number`
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The maximum value (exclusive) of the range.
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#### value
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*Required*
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Type: `number`
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The value to be normalized.
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#### returns
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Type: `number`
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The normalized value.
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## Building and Releasing
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- `npm test`: tests, linting, coverage and style checks.
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- `npm run watch`: autotest mode for active development.
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- `npm run debug`: run tests without coverage (istanbul can obscure line #'s)
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Release via `cut-release` tool.
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## License
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MIT © [James Talmage](http://github.com/jamestalmage)
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