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chore: add isProbabilityArray (issue #6976) #6981

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27 changes: 27 additions & 0 deletions lib/node_modules/@stdlib/assert/is-probability-array/lib/main.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
'use strict';

function isProbability(x) {
return typeof x === 'number' && x >= 0 && x <= 1;
}

/**
* Tests if a value is an array-like object containing only probabilities (numbers between 0 and 1).
*
* @param {*} value - value to test
* @returns {boolean} boolean indicating whether value is a probability array
*/
function isProbabilityArray(value) {
var i;
if (!Array.isArray(value)) {
return false;
}
for (i = 0; i < value.length; i++) {
if (!isProbability(value[i])) {
return false;
}
}
return true;
}

// EXPORTS //
module.exports = isProbabilityArray;
74 changes: 15 additions & 59 deletions lib/node_modules/@stdlib/assert/is-probability-array/test/test.js
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Expand Up @@ -20,75 +20,31 @@

// MODULES //

var tape = require( 'tape' );
var Float64Array = require( '@stdlib/array/float64' );
var Number = require( '@stdlib/number/ctor' );
var isProbabilityArray = require( './../lib' );

'use strict';

// TESTS //
var tape = require('tape');
var isProbabilityArray = require('./../lib/main.js');

tape( 'main export is a function', function test( t ) {
t.ok( true, __filename );
t.strictEqual( typeof isProbabilityArray, 'function', 'main export is a function' );
tape('main export is a function', function test(t) {
t.ok(typeof isProbabilityArray === 'function', 'main export is a function');
t.end();
});

tape( 'the function tests for an array-like object containing only probabilities', function test( t ) {
var arr;

arr = [ 0.9, new Number( 0.8 ), 0.0 ]; // eslint-disable-line no-new-wrappers
t.equal( isProbabilityArray( arr ), true, 'returns true' );

arr = new Float64Array( [ 0.9, 0.5, 0.3 ] );
t.equal( isProbabilityArray( arr ), true, 'returns true' );

arr = {
'length': 2,
'0': 0.3,
'1': 0.8
};
t.equal( isProbabilityArray( arr ), true, 'returns true' );

arr = [ 0.9, '3', null ];
t.equal( isProbabilityArray( arr ), false, 'returns false' );

arr = new Float64Array( [ 0.9, NaN, 0.3 ] );
t.equal( isProbabilityArray( arr ), false, 'returns false' );

tape('returns true for arrays of probabilities', function test(t) {
t.equal(isProbabilityArray([0, 0.5, 1]), true);
t.equal(isProbabilityArray([0.2, 0.8]), true);
t.end();
});

tape( 'the function provides a method to test for an array-like object containing only primitive probabilities', function test( t ) {
var arr;

arr = [ 1.0, 0.0 ];
t.equal( isProbabilityArray.primitives( arr ), true, 'returns true' );

arr = new Float64Array( [ 0.9, 0.5, 0.3 ] );
t.equal( isProbabilityArray( arr ), true, 'returns true' );

arr = [ new Number( 5 ), 1.0, 1.0 ]; // eslint-disable-line no-new-wrappers
t.equal( isProbabilityArray.primitives( arr ), false, 'returns false' );

tape('returns false for arrays with out-of-range numbers', function test(t) {
t.equal(isProbabilityArray([0, -0.1, 0.5]), false);
t.equal(isProbabilityArray([1.2, 0.3]), false);
t.end();
});

tape( 'the function provides a method to test for an array-like object containing only containing only Number objects whose values are probabilities', function test( t ) {
var arr;

arr = [ new Number( 0.5 ), new Number( 0.5 ) ]; // eslint-disable-line no-new-wrappers
t.equal( isProbabilityArray.objects( arr ), true, 'returns true' );

arr = {
'length': 2,
'0': new Number( 0.3 ), // eslint-disable-line no-new-wrappers
'1': new Number( 0.8 ) // eslint-disable-line no-new-wrappers
};
t.equal( isProbabilityArray( arr ), true, 'returns true' );

arr = [ 0.5, 0.0 ];
t.equal( isProbabilityArray.objects( arr ), false, 'returns false' );

tape('returns false for non-arrays', function test(t) {
t.equal(isProbabilityArray('not an array'), false);
t.equal(isProbabilityArray(0.5), false);
t.equal(isProbabilityArray(null), false);
t.end();
});