4.9 KiB
4.9 KiB
iterMap
Create an iterator which invokes a unary function accepting a single numeric argument for each iterated value.
Usage
var iterMap = require( '@stdlib/math/iter/tools/map' );
iterMap( iterator, fcn[, options] )
Returns an iterator which invokes a unary function
accepting a single numeric argument for each iterated value.
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 protocol-compliant object has the following properties:
- next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a
value
property and adone
property having aboolean
value indicating whether the iterator is finished. - return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.
The invoked function
is provided one argument:
value
: iterated value
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 yields a non-numeric value. Default:
NaN
.
By default, the function returns an iterator which returns NaN
when an input iterator yields a non-numeric value. To specify a different return value, set the invalid
option.
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
// ...
Notes
Examples
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 );
}