time-to-botec

README.md (6979B)

---

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 # iterMap3
 
 > Create an [iterator][mdn-iterator-protocol] which invokes a ternary function accepting numeric arguments for each iterated value.
 
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 <section class="intro">
 
 </section>
 
 <!-- /.intro -->
 
 <!-- Package usage documentation. -->
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var iterMap3 = require( '@stdlib/math/iter/tools/map3' );
 ```
 
 #### iterMap3( iter0, iter1, iter2, fcn\[, options] )
 
 Returns an [iterator][mdn-iterator-protocol] which invokes a ternary `function` accepting numeric arguments for each iterated value.
 
 ```javascript
 var array2iterator = require( '@stdlib/array/to-iterator' );
 var clamp = require( '@stdlib/math/base/special/clamp' );
 
 var x = array2iterator( [ 1.0, -2.0, 3.0, 14.0 ] );
 var min = array2iterator( [ 1.0, 0.0, -1.0, 1.0 ] );
 var max = array2iterator( [ 10.0, 10.0, 2.0, 10.0 ] );
 
 var it = iterMap3( x, min, max, clamp );
 // returns <Object>
 
 var r = it.next().value;
 // returns 1.0
 
 r = it.next().value;
 // returns 0.0
 
 r = it.next().value;
 // returns 2.0
 
 // ...
 ```
 
 The returned [iterator][mdn-iterator-protocol] protocol-compliant object has the following properties:
 
 -   **next**: function which returns an [iterator][mdn-iterator-protocol] protocol-compliant object containing the next iterated value (if one exists) assigned to a `value` property and a `done` property having a `boolean` value indicating whether the iterator is finished.
 -   **return**: function which closes an [iterator][mdn-iterator-protocol] and returns a single (optional) argument in an [iterator][mdn-iterator-protocol] protocol-compliant object.
 
 The invoked `function` is provided three arguments:
 
 -   `x`: iterated value from first input [iterator][mdn-iterator-protocol].
 -   `y`: iterated value from second input [iterator][mdn-iterator-protocol].
 -   `z`: iterated value from third input [iterator][mdn-iterator-protocol].
 
 ```javascript
 var array2iterator = require( '@stdlib/array/to-iterator' );
 
 function fcn( x, y, z ) {
     return x + y + z + 10;
 }
 
 var it1 = array2iterator( [ 1, 2, 3, 4 ] );
 var it2 = array2iterator( [ 1, 2, 3, 4 ] );
 var it3 = array2iterator( [ 1, 2, 3, 4 ] );
 
 var it = iterMap3( it1, it2, it3, fcn );
 // returns <Object>
 
 var r = it.next().value;
 // returns 13
 
 r = it.next().value;
 // returns 16
 
 r = it.next().value;
 // returns 19
 
 // ...
 ```
 
 The function supports the following `options`:
 
 -   **invalid**: return value when an input [iterator][mdn-iterator-protocol] yields a non-numeric value. Default: `NaN`.
 
 By default, the function returns an [iterator][mdn-iterator-protocol] which returns `NaN` when an input [iterator][mdn-iterator-protocol] yields a non-numeric value. To specify a different return value, set the `invalid` option.
 
 ```javascript
 var array2iterator = require( '@stdlib/array/to-iterator' );
 var clamp = require( '@stdlib/math/base/special/clamp' );
 
 var it1 = array2iterator( [ '1.0', '2.0', '3.0' ] );
 var it2 = array2iterator( [ 0.0, 0.0, 0.0 ] );
 var it3 = array2iterator( [ 10.0, 10.0, 10.0 ] );
 
 var opts = {
     'invalid': null
 };
 var it = iterMap3( it1, it2, it3, clamp, opts );
 // returns <Object>
 
 var v = it.next().value;
 // returns null
 
 v = it.next().value;
 // returns null
 
 // ...
 ```
 
 If provided a numeric value as an [`iterator`][mdn-iterator-protocol] argument, the value is broadcast as an **infinite** [iterator][mdn-iterator-protocol] which **always** returns the provided value.
 
 ```javascript
 var array2iterator = require( '@stdlib/array/to-iterator' );
 var clamp = require( '@stdlib/math/base/special/clamp' );
 
 var x = array2iterator( [ -1.0, 20.0 ] );
 
 var it = iterMap3( x, 0.0, 10.0, clamp );
 // returns <Object>
 
 var v = it.next().value;
 // returns 0.0
 
 v = it.next().value;
 // returns 10.0
 
 var bool = it.next().done;
 // returns true
 ```
 
 </section>
 
 <!-- /.usage -->
 
 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="notes">
 
 ## Notes
 
 -   If an iterated value is non-numeric (including `NaN`), the returned [iterator][mdn-iterator-protocol] returns `NaN`. If non-numeric iterated values are possible, you are advised to provide an [`iterator`][mdn-iterator-protocol] which type checks and handles non-numeric values accordingly.
 -   The length of the returned [iterator][mdn-iterator-protocol] is equal to the length of the shortest provided [iterator][mdn-iterator-protocol]. In other words, the returned [iterator][mdn-iterator-protocol] ends once **one** of the provided [iterators][mdn-iterator-protocol] ends.
 -   If an environment supports `Symbol.iterator` **and** a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
 
 </section>
 
 <!-- /.notes -->
 
 <!-- Package usage examples. -->
 
 <section class="examples">
 
 ## Examples
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var uniform = require( '@stdlib/random/iter/uniform' );
 var clamp = require( '@stdlib/math/base/special/clamp' );
 var iterMap3 = require( '@stdlib/math/iter/tools/map3' );
 
 // Create seeded iterators for generating pseudorandom numbers:
 var x = uniform( 0.0, 10.0, {
     'seed': 1234,
     'iter': 10
 });
 
 var min = uniform( 0.0, 1.0, {
     'seed': 4567,
     'iter': 10
 });
 
 var max = uniform( 9.0, 10.0, {
     'seed': 7895,
     'iter': 10
 });
 
 // Create an iterator which consumes the pseudorandom number iterators:
 var it = iterMap3( x, min, max, clamp );
 
 // Perform manual iteration...
 var r;
 while ( true ) {
     r = it.next();
     if ( r.done ) {
         break;
     }
     console.log( r.value );
 }
 ```
 
 </section>
 
 <!-- /.examples -->
 
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 </section>
 
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 <section class="links">
 
 [mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol
 
 </section>
 
 <!-- /.links -->