@stdlib/random-iter-cosine
Version:
Create an iterator for generating pseudorandom numbers drawn from a raised cosine distribution.
253 lines (231 loc) • 6.91 kB
JavaScript
/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
;
// MODULES //
var setReadOnly = require( '@stdlib/utils-define-nonenumerable-read-only-property' );
var setReadOnlyAccessor = require( '@stdlib/utils-define-nonenumerable-read-only-accessor' );
var setReadWriteAccessor = require( '@stdlib/utils-define-nonenumerable-read-write-accessor' );
var constantFunction = require( '@stdlib/utils-constant-function' );
var noop = require( '@stdlib/utils-noop' );
var assign = require( '@stdlib/object-assign' );
var isNumber = require( '@stdlib/assert-is-number' ).isPrimitive;
var isnan = require( '@stdlib/math-base-assert-is-nan' );
var isObject = require( '@stdlib/assert-is-plain-object' );
var isNonNegativeInteger = require( '@stdlib/assert-is-nonnegative-integer' ).isPrimitive;
var isPositive = require( '@stdlib/assert-is-positive-number' ).isPrimitive;
var hasOwnProp = require( '@stdlib/assert-has-own-property' );
var MAX_VALUE = require( '@stdlib/constants-float64-max' );
var rcosine = require( '@stdlib/random-base-cosine' ).factory;
var iteratorSymbol = require( '@stdlib/symbol-iterator' );
var format = require( '@stdlib/string-format' );
// MAIN //
/**
* Returns an iterator for generating pseudorandom numbers drawn from a raised cosine distribution.
*
* @param {number} mu - location parameter
* @param {PositiveNumber} s - scale parameter
* @param {Options} [options] - function options
* @param {PRNG} [options.prng] - pseudorandom number generator which generates uniformly distributed pseudorandom numbers
* @param {PRNGSeedMT19937} [options.seed] - pseudorandom number generator seed
* @param {PRNGStateMT19937} [options.state] - pseudorandom number generator state
* @param {boolean} [options.copy=true] - boolean indicating whether to copy a provided pseudorandom number generator state
* @param {NonNegativeInteger} [options.iter] - number of iterations
* @throws {TypeError} `mu` must be a number
* @throws {TypeError} `s` must be a positive number
* @throws {TypeError} options argument must be an object
* @throws {TypeError} must provide valid options
* @throws {Error} must provide a valid state
* @returns {Iterator} iterator
*
* @example
* var iter = iterator( -1.0, 3.0 );
*
* var r = iter.next().value;
* // returns <number>
*
* r = iter.next().value;
* // returns <number>
*
* r = iter.next().value;
* // returns <number>
*
* // ...
*/
function iterator( mu, s, options ) {
var opts;
var iter;
var rand;
var FLG;
var i;
if ( !isNumber( mu ) || isnan( mu ) ) {
throw new TypeError( format( 'invalid argument. First argument must be a number and not NaN. Value: `%s`.', mu ) );
}
if ( !isPositive( s ) ) {
throw new TypeError( format( 'invalid argument. Second argument must be a positive number. Value: `%s`.', s ) );
}
if ( arguments.length > 2 ) {
if ( !isObject( options ) ) {
throw new TypeError( format( 'invalid argument. Options argument must be an object. Value: `%s`.', options ) );
}
opts = assign( {}, options );
if ( hasOwnProp( opts, 'iter' ) ) {
if ( !isNonNegativeInteger( opts.iter ) ) {
throw new TypeError( format( 'invalid option. `%s` option must be a nonnegative integer. Option: `%s`.', 'iter', opts.iter ) );
}
} else {
opts.iter = MAX_VALUE;
}
rand = rcosine( mu, s, opts );
if ( opts.prng === void 0 && opts.copy !== false ) {
opts.state = rand.state; // cache a copy of the PRNG state
}
} else {
rand = rcosine( mu, s );
opts = {
'iter': MAX_VALUE,
'state': rand.state // cache a copy of the PRNG state
};
}
i = 0;
// Create an iterator protocol-compliant object:
iter = {};
setReadOnly( iter, 'next', next );
setReadOnly( iter, 'return', end );
if ( opts && opts.prng ) {
setReadOnly( iter, 'seed', null );
setReadOnly( iter, 'seedLength', null );
setReadWriteAccessor( iter, 'state', constantFunction( null ), noop );
setReadOnly( iter, 'stateLength', null );
setReadOnly( iter, 'byteLength', null );
} else {
setReadOnlyAccessor( iter, 'seed', getSeed );
setReadOnlyAccessor( iter, 'seedLength', getSeedLength );
setReadWriteAccessor( iter, 'state', getState, setState );
setReadOnlyAccessor( iter, 'stateLength', getStateLength );
setReadOnlyAccessor( iter, 'byteLength', getStateSize );
}
setReadOnly( iter, 'PRNG', rand.PRNG );
// If an environment supports `Symbol.iterator`, make the iterator iterable:
if ( iteratorSymbol ) {
setReadOnly( iter, iteratorSymbol, factory );
}
return iter;
/**
* Returns an iterator protocol-compliant object containing the next iterated value.
*
* @private
* @returns {Object} iterator protocol-compliant object
*/
function next() {
i += 1;
if ( FLG || i > opts.iter ) {
return {
'done': true
};
}
return {
'value': rand(),
'done': false
};
}
/**
* Finishes an iterator.
*
* @private
* @param {*} [value] - value to return
* @returns {Object} iterator protocol-compliant object
*/
function end( value ) {
FLG = true;
if ( arguments.length ) {
return {
'value': value,
'done': true
};
}
return {
'done': true
};
}
/**
* Returns a new iterator.
*
* @private
* @returns {Iterator} iterator
*/
function factory() {
return iterator( mu, s, opts );
}
/**
* Returns the PRNG seed.
*
* @private
* @returns {PRNGSeedMT19937} seed
*/
function getSeed() {
return rand.PRNG.seed;
}
/**
* Returns the PRNG seed length.
*
* @private
* @returns {PositiveInteger} seed length
*/
function getSeedLength() {
return rand.PRNG.seedLength;
}
/**
* Returns the PRNG state length.
*
* @private
* @returns {PositiveInteger} state length
*/
function getStateLength() {
return rand.PRNG.stateLength;
}
/**
* Returns the PRNG state size (in bytes).
*
* @private
* @returns {PositiveInteger} state size (in bytes)
*/
function getStateSize() {
return rand.PRNG.byteLength;
}
/**
* Returns the current pseudorandom number generator state.
*
* @private
* @returns {PRNGStateMT19937} current state
*/
function getState() {
return rand.PRNG.state;
}
/**
* Sets the pseudorandom number generator state.
*
* @private
* @param {PRNGStateMT19937} s - generator state
* @throws {Error} must provide a valid state
*/
function setState( s ) {
rand.PRNG.state = s;
}
}
// EXPORTS //
module.exports = iterator;