feat!: refactor Fligner-Killeen test to return class instance and be more performant

lib/node_modules/@stdlib/stats/fligner-test/README.md

@@ -36,7 +36,7 @@ limitations under the License.
 var flignerTest = require( '@stdlib/stats/fligner-test' );
 ```
 
-#### flignerTest( a\[,b,...,k]\[, opts] )
+#### flignerTest( a\[,b,...,k]\[, options] )
 
 For input arrays `a`, `b`, ... holding numeric observations, this function calculates the Fligner-Killeen test, which tests the null hypothesis that the variances in all `k` groups are the same.
 
@@ -46,7 +46,9 @@ var x = [ 2.9, 3.0, 2.5, 2.6, 3.2 ];
 var y = [ 3.8, 2.7, 4.0, 2.4 ];
 var z = [ 2.8, 3.4, 3.7, 2.2, 2.0 ];
 
-var out = flignerTest( x, y, z );
+var res = flignerTest( x, y, z );
+
+var o = res.toJSON();
 /* returns
     {
         'rejected': false,
@@ -106,23 +108,34 @@ var out = flignerTest( arr, {
 });
 ```
 
-The returned object comes with a `.print()` method which when invoked will print a formatted output of the results of the hypothesis test. `print` accepts a `digits` option that controls the number of decimal digits displayed for the outputs and a `decision` option, which when set to `false` will hide the test decision.
+The function returns a results `object` having the following properties:
+
+-   **alpha**: significance level.
+-   **rejected**: `boolean` indicating the test decision.
+-   **pValue**: test p-value.
+-   **statistic**: test statistic.
+-   **df**: degrees of freedom.
+-   **method**: test name.
+-   **toString**: serializes results as formatted test output.
+-   **toJSON**: serializes results as a JSON object.
+
+The returned object comes with a `.toString()` method which when invoked will print a formatted output of the results of the hypothesis test. `toString` accepts a `digits` option that controls the number of decimal digits displayed for the outputs and a `decision` option, which when set to `false` will hide the test decision.
 
 ```javascript
 var x = [ 2.9, 3.0, 2.5, 2.6, 3.2 ];
 var y = [ 3.8, 2.7, 4.0, 2.4 ];
 var z = [ 2.8, 3.4, 3.7, 2.2, 2.0 ];
 
 var out = flignerTest( x, y, z );
-console.log( out.print() );
-/* =>
+var table = out.toString();
+/* returns
     Fligner-Killeen test of homogeneity of variances
 
-    Null hypothesis: The variances in all groups are the same.
+    Null hypothesis: The variances in all groups are the same
 
         pValue: 0.0739
         statistic: 5.2092
-        df: 2
+        degrees of freedom: 2
 
     Test Decision: Fail to reject null in favor of alternative at 5% significance level
 */
@@ -158,15 +171,15 @@ var out = flignerTest( x, y, z );
     }
 */
 
-var table = out.print();
+var table = out.toString();
 /* returns
     Fligner-Killeen test of homogeneity of variances
 
-    Null hypothesis: The variances in all groups are the same.
+    Null hypothesis: The variances in all groups are the same
 
         pValue: 0.0739
         statistic: 5.2092
-        df: 2
+        degrees of freedom: 2
 
     Test Decision: Fail to reject null in favor of alternative at 5% significance level
 */

lib/node_modules/@stdlib/stats/fligner-test/docs/repl.txt

@@ -40,8 +40,11 @@
     out.df: Object
         Degrees of freedom.
 
-    out.print: Function
-        Function to print formatted output.
+    out.toString: Function
+        Serializes results as formatted output.
+
+    out.toJSON: Function
+        Serializes results as JSON.
 
     Examples
     --------
@@ -50,7 +53,11 @@
     > var y = [ 3.8, 2.7, 4.0, 2.4 ];
     > var z = [ 2.8, 3.4, 3.7, 2.2, 2.0 ];
 
-    > var out = {{alias}}( x, y, z )
+    > var out = {{alias}}( x, y, z );
+    > var o = out.toJSON()
+    {...}
+    > out.toString()
+    <string>
 
     > var arr = [ 2.9, 3.0, 2.5, 2.6, 3.2,
     ...     3.8, 2.7, 4.0, 2.4,
@@ -61,7 +68,11 @@
     ...     'b', 'b', 'b', 'b',
     ...     'c', 'c', 'c', 'c', 'c'
     ... ];
-    > out = {{alias}}( arr, { 'groups': groups } )
+    > out = {{alias}}( arr, { 'groups': groups } );
+    > o = out.toJSON()
+    {...}
+    > out.toString()
+    <string>
 
     See Also
     --------

lib/node_modules/@stdlib/stats/fligner-test/docs/types/index.d.ts

@@ -34,7 +34,7 @@
 	/**
 	* Array of group indicators.
 	*/
 	groups?: Array<any>;
 }
 
 /**
@@ -72,9 +72,14 @@
 	df: number;
 
 	/**
-	* Function to print formatted output.
+	* Serializes results as formatted test output.
 	*/
-	print: Function;
+	toString: Function; // FIXME: provide better type
+
+	/**
+	* Serializes results as JSON.
+	*/
+	toJSON: Function; // FIXME: provide better type
 }
 
 /**

lib/node_modules/@stdlib/stats/fligner-test/examples/index.js

@@ -30,5 +30,5 @@ console.log( 'Output object: ' );
 console.dir( out );
 console.log( '\n' );
 
-var table = out.print();
+var table = out.toString();
 console.log( table );

lib/node_modules/@stdlib/stats/fligner-test/lib/main.js

@@ -22,40 +22,20 @@
 
 var isCollection = require( '@stdlib/assert/is-collection' );
 var isPlainObject = require( '@stdlib/assert/is-plain-object' );
-var setReadOnly = require( '@stdlib/utils/define-read-only-property' );
 var objectKeys = require( '@stdlib/utils/keys' );
 var qnorm = require( '@stdlib/stats/base/dists/normal/quantile' );
 var chisqCDF = require( '@stdlib/stats/base/dists/chisquare/cdf' );
 var group = require( '@stdlib/utils/group' );
 var ranks = require( '@stdlib/stats/ranks' );
-var abs = require( '@stdlib/math/base/special/abs' );
+var abs = require( '@stdlib/math/strided/special/abs' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var indexOf = require( '@stdlib/utils/index-of' );
 var format = require( '@stdlib/string/format' );
+var filled = require( '@stdlib/array/base/filled' );
+var Float64Array = require( '@stdlib/array/float64' );
 var median = require( './median.js' );
 var validate = require( './validate.js' );
-var print = require( './print.js' ); // eslint-disable-line stdlib/no-redeclare
-
-
-// FUNCTIONS //
-
-/**
-* Returns an array of a chosen length filled with the supplied value.
-*
-* @private
-* @param {*} val - value to repeat
-* @param {NonNegativeInteger} len - array length
-* @returns {Array} filled array
-*/
-function repeat( val, len ) {
-	var out = new Array( len );
-	var i;
-
-	for ( i = 0; i < len; i++ ) {
-		out[ i ] = val;
-	}
-	return out;
-}
+var Results = require( './results.js' );
 
 
 // MAIN //
@@ -102,7 +82,6 @@ function fligner() {
 	var stat;
 	var err;
 	var loc;
-	var out;
 	var df;
 	var M2;
 	var a;
@@ -137,7 +116,7 @@ function fligner() {
 		groups = [];
 		for ( i = 0; i < ngroups; i++ ) {
 			args.push( arguments[ i ] );
-			groups = groups.concat( repeat( i, arguments[ i ].length ) );
+			groups = groups.concat( filled( i, arguments[ i ].length ) );
 		}
 	}
 	if ( opts.alpha === void 0 ) {
@@ -163,15 +142,13 @@ function fligner() {
 		x = x.concat( args[ i ] );
 	}
 	n = x.length;
-	xabs = new Array( n );
-	for ( i = 0; i < n; i++ ) {
-		xabs[ i ] = abs( x[ i ] );
-	}
+	xabs = new Float64Array( n );
+	abs( n, 'float64', x, 1, 'float64', xabs, 1 );
 	scores = ranks( xabs );
-	a = new Array( n );
+	a = new Float64Array( n );
 	mean = 0.0;
 	M2 = 0.0;
-	sums = repeat( 0.0, ngroups );
+	sums = filled( 0.0, ngroups );
 	for ( i = 0; i < n; i++ ) {
 		a[ i ] = qnorm( ( 1.0 + ( scores[ i ]/(n+1) ) ) / 2.0, 0.0, 1.0 );
 		sums[ ( levels ) ? indexOf( levels, groups[i] ) : groups[i] ] += a[ i ];
@@ -188,15 +165,7 @@ function fligner() {
 	df = ngroups - 1;
 	pval = 1.0 - chisqCDF( stat, df );
 
-	out = {};
-	setReadOnly( out, 'rejected', pval <= alpha );
-	setReadOnly( out, 'alpha', alpha );
-	setReadOnly( out, 'pValue', pval );
-	setReadOnly( out, 'statistic', stat );
-	setReadOnly( out, 'df', df );
-	setReadOnly( out, 'method', 'Fligner-Killeen test of homogeneity of variances' );
-	setReadOnly( out, 'print', print );
-	return out;
+	return new Results( pval, opts.alpha, stat, df );
 }