iterMap
Create an iterator which invokes a function for each iterated value.
Usage
var iterMap = require( '@stdlib/iter/map' );
iterMap( iterator, fcn[, thisArg] )
Returns an iterator which invokes a function for each iterated value.
var array2iterator = require( '@stdlib/array/to-iterator' );
function fcn( v ) {
return v * 10.0;
}
var it = iterMap( array2iterator( [ 1, 2, 3, 4 ] ), fcn );
// returns <Object>
var r = it.next().value;
// returns 10.0
r = it.next().value;
// returns 20.0
r = it.next().value;
// returns 30.0
// ...
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
valueproperty and adoneproperty having abooleanvalue 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 two arguments:
- value: iterated value.
- index: iteration index (zero-based).
var array2iterator = require( '@stdlib/array/to-iterator' );
function fcn( v, i ) {
return v * (i+1);
}
var it = iterMap( array2iterator( [ 1, 2, 3, 4 ] ), fcn );
// returns <Object>
var r = it.next().value;
// returns 1
r = it.next().value;
// returns 4
r = it.next().value;
// returns 9
// ...
To set the function execution context, provide a thisArg.
var array2iterator = require( '@stdlib/array/to-iterator' );
function fcn( v ) {
this.count += 1;
return v * 10.0;
}
var ctx = {
'count': 0
};
var it = iterMap( array2iterator( [ 1, 2, 3, 4 ] ), fcn, ctx );
// returns <Object>
var r = it.next().value;
// returns 10.0
r = it.next().value;
// returns 20.0
r = it.next().value;
// returns 30.0
var count = ctx.count;
// returns 3
Notes
Examples
var randu = require( '@stdlib/random/iter/randu' );
var iterMap = require( '@stdlib/iter/map' );
function scale( v ) {
return v * 10.0;
}
// Create a seeded iterator for generating pseudorandom numbers:
var rand = randu({
'seed': 1234,
'iter': 10
});
// Create an iterator which scales the generated numbers:
var it = iterMap( rand, scale );
// Perform manual iteration...
var r;
while ( true ) {
r = it.next();
if ( r.done ) {
break;
}
console.log( r.value );
}