Refactor to ignore undefined return values

This allows replicating `msk*` interface behavior.

Author: kgryte

lib/node_modules/@stdlib/stats/base/min-by/README.md

@@ -161,6 +161,7 @@ var v = minBy.ndarray( 3, x, 1, x.length-3, accessor );
 
 -   If `N <= 0`, both functions return `NaN`.
 -   A provided callback function should return a numeric value.
+-   If a provided callback function does not return any value (or equivalently, explicitly returns `undefined`), the value is **ignored**.
 -   When possible, prefer using [`dmin`][@stdlib/stats/base/dmin], [`smin`][@stdlib/stats/base/smin], and/or [`min`][@stdlib/stats/base/min], as, depending on the environment, these interfaces are likely to be significantly more performant.
 
 </section>

lib/node_modules/@stdlib/stats/base/min-by/docs/repl.txt

@@ -19,6 +19,9 @@
 
     The callback function should return a numeric value.
 
+    If the callback function does not return any value (or equivalently,
+    explicitly returns `undefined`), the value is ignored.
+
     Parameters
     ----------
     N: integer

lib/node_modules/@stdlib/stats/base/min-by/docs/types/index.d.ts

@@ -27,15 +27,15 @@ import { Collection } from '@stdlib/types/object';
 *
 * @returns accessed value
 */
-type Nullary = () => number;
+type Nullary = () => number | void;
 
 /**
 * Returns an accessed value.
 *
 * @param value - array element
 * @returns accessed value
 */
-type Unary = ( value: any ) => number;
+type Unary = ( value: any ) => number | void;
 
 /**
 * Returns an accessed value.
@@ -44,7 +44,7 @@ type Unary = ( value: any ) => number;
 * @param aidx - array index
 * @returns accessed value
 */
-type Binary = ( value: any, aidx: number ) => number;
+type Binary = ( value: any, aidx: number ) => number | void;
 
 /**
 * Returns an accessed value.
@@ -54,7 +54,7 @@ type Binary = ( value: any, aidx: number ) => number;
 * @param sidx - strided index (offset + aidx*stride)
 * @returns accessed value
 */
-type Tertiary = ( value: any, aidx: number, sidx: number ) => number;
+type Tertiary = ( value: any, aidx: number, sidx: number ) => number | void;
 
 /**
 * Returns an accessed value.
@@ -65,7 +65,7 @@ type Tertiary = ( value: any, aidx: number, sidx: number ) => number;
 * @param array - input array
 * @returns accessed value
 */
-type Quaternary = ( value: any, aidx: number, sidx: number, array: Collection ) => number; // tslint-disable-line max-line-length
+type Quaternary = ( value: any, aidx: number, sidx: number, array: Collection ) => number | void; // tslint-disable-line max-line-length
 
 /**
 * Returns an accessed value.
@@ -94,7 +94,7 @@ interface Routine {
 	*     -   `sidx`: strided index (offset + aidx*stride)
 	*     -   `array`: input array
 	*
-	* -   The callback function should return a numeric value.
+	* -   The callback function should return a numeric value. If the callback function does not return any value (or equivalently, explicitly returns `undefined`), the value is ignored.
 	*
 	* @param N - number of indexed elements
 	* @param x - input array
@@ -127,7 +127,7 @@ interface Routine {
 	*     -   `sidx`: strided index (offset + aidx*stride)
 	*     -   `array`: input array
 	*
-	* -   The callback function should return a numeric value.
+	* -   The callback function should return a numeric value. If the callback function does not return any value (or equivalently, explicitly returns `undefined`), the value is ignored.
 	*
 	* @param N - number of indexed elements
 	* @param x - input array
@@ -162,7 +162,7 @@ interface Routine {
 *     -   `sidx`: strided index (offset + aidx*stride)
 *     -   `array`: input array
 *
-* -   The callback function should return a numeric value.
+* -   The callback function should return a numeric value. If the callback function does not return any value (or equivalently, explicitly returns `undefined`), the value is ignored.
 *
 * @param N - number of indexed elements
 * @param x - input array

lib/node_modules/@stdlib/stats/base/min-by/lib/min_by.js

@@ -56,17 +56,34 @@ function minBy( N, x, stride, clbk, thisArg ) {
 		return NaN;
 	}
 	if ( N === 1 || stride === 0 ) {
-		return clbk.call( thisArg, x[ 0 ], 0, 0, x );
+		v = clbk.call( thisArg, x[ 0 ], 0, 0, x );
+		if ( v === void 0 ) {
+			return NaN;
+		}
+		return v;
 	}
 	if ( stride < 0 ) {
 		ix = (1-N) * stride;
 	} else {
 		ix = 0;
 	}
-	min = clbk.call( thisArg, x[ ix ], 0, ix, x );
-	for ( i = 1; i < N; i++ ) {
+	for ( i = 0; i < N; i++ ) {
+		min = clbk.call( thisArg, x[ ix ], i, ix, x );
+		if ( min !== void 0 ) {
+			break;
+		}
+		ix += stride;
+	}
+	if ( i === N ) {
+		return NaN;
+	}
+	i += 1;
+	for ( i; i < N; i++ ) {
 		ix += stride;
 		v = clbk.call( thisArg, x[ ix ], i, ix, x );
+		if ( v === void 0 ) {
+			continue;
+		}
 		if ( isnan( v ) ) {
 			return v;
 		}

lib/node_modules/@stdlib/stats/base/min-by/lib/ndarray.js

@@ -57,13 +57,30 @@ function minBy( N, x, stride, offset, clbk, thisArg ) {
 		return NaN;
 	}
 	if ( N === 1 || stride === 0 ) {
-		return clbk.call( thisArg, x[ 0 ], 0, 0, x );
+		v = clbk.call( thisArg, x[ 0 ], 0, 0, x );
+		if ( v === void 0 ) {
+			return NaN;
+		}
+		return v;
 	}
 	ix = offset;
-	min = clbk.call( thisArg, x[ ix ], 0, ix, x );
-	for ( i = 1; i < N; i++ ) {
+	for ( i = 0; i < N; i++ ) {
+		min = clbk.call( thisArg, x[ ix ], i, ix, x );
+		if ( min !== void 0 ) {
+			break;
+		}
+		ix += stride;
+	}
+	if ( i === N ) {
+		return NaN;
+	}
+	i += 1;
+	for ( i; i < N; i++ ) {
 		ix += stride;
 		v = clbk.call( thisArg, x[ ix ], i, ix, x );
+		if ( v === void 0 ) {
+			continue;
+		}
 		if ( isnan( v ) ) {
 			return v;
 		}

lib/node_modules/@stdlib/stats/base/min-by/test/test.min_by.js

@@ -31,6 +31,9 @@ var minBy = require( './../lib/min_by.js' );
 // FUNCTIONS //
 
 function accessor( v ) {
+	if ( v === void 0 ) {
+		return;
+	}
 	return v * 2.0;
 }
 
@@ -72,6 +75,15 @@ tape( 'the function calculates the minimum value of a strided array via a callba
 	v = minBy( x.length, x, 1, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
+	x = new Array( 5 ); // sparse array
+	v = minBy( x.length, x, 1, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	x = new Array( 5 ); // sparse array
+	x[ 2 ] = 1.0;
+	v = minBy( x.length, x, 1, accessor );
+	t.strictEqual( v, 2.0, 'returns expected value' );
+
 	t.end();
 });
 
@@ -99,6 +111,11 @@ tape( 'if provided an `N` parameter equal to `1`, the function returns the first
 	v = minBy( 1, x, 1, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
+	x = new Array( 1 ); // sparse array
+
+	v = minBy( 1, x, 1, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
 	t.end();
 });
 
@@ -157,6 +174,11 @@ tape( 'if provided a `stride` parameter equal to `0`, the function returns the f
 	v = minBy( x.length, x, 0, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
+	x = new Array( 1 ); // sparse array
+
+	v = minBy( 1, x, 0, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
 	t.end();
 });
 

lib/node_modules/@stdlib/stats/base/min-by/test/test.ndarray.js

@@ -30,6 +30,9 @@ var minBy = require( './../lib/ndarray.js' );
 // FUNCTIONS //
 
 function accessor( v ) {
+	if ( v === void 0 ) {
+		return;
+	}
 	return v * 2.0;
 }
 
@@ -71,6 +74,15 @@ tape( 'the function calculates the minimum value of a strided array via a callba
 	v = minBy( x.length, x, 1, 0, accessor );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
+	x = new Array( 5 ); // sparse array
+	v = minBy( x.length, x, 1, 0, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	x = new Array( 5 ); // sparse array
+	x[ 2 ] = 1.0;
+	v = minBy( x.length, x, 1, 0, accessor );
+	t.strictEqual( v, 2.0, 'returns expected value' );
+
 	t.end();
 });
 
@@ -98,6 +110,11 @@ tape( 'if provided an `N` parameter equal to `1`, the function returns the first
 	v = minBy( 1, x, 1, 0, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
+	x = new Array( 1 ); // sparse array
+
+	v = minBy( 1, x, 1, 0, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
 	t.end();
 });
 
@@ -156,6 +173,11 @@ tape( 'if provided a `stride` parameter equal to `0`, the function returns the f
 	v = minBy( x.length, x, 0, 0, accessor );
 	t.strictEqual( v, 2.0, 'returns expected value' );
 
+	x = new Array( 1 ); // sparse array
+
+	v = minBy( 1, x, 0, 0, accessor );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
 	t.end();
 });