stdlib-js
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</summary>
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iterMap
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Create an [iterator][mdn-iterator-protocol] which invokes a unary function accepting a single numeric argument for each iterated value.
bash
npm install @stdlib/math-iter-tools-map
javascript
var iterMap = require( '@stdlib/math-iter-tools-map' );
#### iterMap( iterator, fcn[, options] )
Returns an [iterator][mdn-iterator-protocol] which invokes a unary function accepting a single numeric argument for each iterated value.
javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
var sin = require( '@stdlib/math-base-special-sin' );
var it = iterMap( array2iterator( [ 1, 2, 3, 4 ] ), sin );
// returns <Object>
var r = it.next().value;
// returns <number>
r = it.next().value;
// returns <number>
r = it.next().value;
// returns <number>
// ...
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 one argument:
- value: iterated value
javascript
var array2iterator = require( '@stdlib/array-to-iterator' );
function fcn( v ) {
return v + 10;
}
var it = iterMap( array2iterator( [ 1, 2, 3, 4 ] ), fcn );
// returns <Object>
var r = it.next().value;
// returns 11
r = it.next().value;
// returns 12
r = it.next().value;
// returns 13
// ...
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 sin = require( '@stdlib/math-base-special-sin' );
var opts = {
'invalid': null
};
var it = iterMap( array2iterator( [ '1', '2', '3' ] ), sin, opts );
// returns <Object>
var v = it.next().value;
// returns null
v = it.next().value;
// returns null
// ...
Symbol.iterator and a provided [iterator][mdn-iterator-protocol] is iterable, the returned [iterator][mdn-iterator-protocol] is iterable.
javascript
var randu = require( '@stdlib/random-iter-randu' );
var sin = require( '@stdlib/math-base-special-sin' );
var iterMap = require( '@stdlib/math-iter-tools-map' );
// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234,
'iter': 10
});
// Create an iterator which consumes the pseudorandom number iterator:
var it = iterMap( rand, sin );
// Perform manual iteration...
var r;
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}
