diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/README.md b/lib/node_modules/@stdlib/stats/incr/nanmape/README.md
new file mode 100644
index 000000000000..1922d9bd7831
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/README.md
@@ -0,0 +1,182 @@
+
+
+# incrnanmape
+
+> Compute the [mean absolute percentage error][mean-absolute-percentage-error] (MAPE) incrementally, ignoring `NaN` values.
+
+
+
+The [mean absolute percentage error][mean-absolute-percentage-error] is defined as
+
+
+
+```math
+\mathop{\mathrm{MAPE}} = \frac{100}{n} \sum_{i=0}^{n-1} \biggl| \frac{a_i - f_i}{a_i} \biggr|
+```
+
+
+
+
+
+where `f_i` is the forecast value and `a_i` is the actual value.
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var incrnanmape = require( '@stdlib/stats/incr/nanmape' );
+```
+
+#### incrnanmape()
+
+Returns an accumulator `function` which incrementally computes the [mean absolute percentage error][mean-absolute-percentage-error].
+
+```javascript
+var accumulator = incrnanmape();
+```
+
+#### accumulator( \[f, a] )
+
+If provided input values `f` and `a`, the accumulator function returns an updated [mean absolute percentage error][mean-absolute-percentage-error]. If not provided input values `f` and `a`, the accumulator function returns the current [mean absolute percentage error][mean-absolute-percentage-error].
+
+```javascript
+var accumulator = incrnanmape();
+
+var m = accumulator( 2.0, 3.0 );
+// returns ~33.33
+
+m = accumulator( 1.0, 4.0 );
+// returns ~54.17
+
+m = accumulator( NaN, 4.0 );
+// returns ~54.17
+
+m = accumulator( 3.0, 5.0 );
+// returns ~49.44
+
+m = accumulator( 3.0, NaN );
+// returns ~49.44
+
+m = accumulator( NaN, NaN );
+// returns ~49.44
+
+m = accumulator();
+// returns ~49.44
+```
+
+
+
+
+
+
+
+## Notes
+
+- Input values are **not** type checked. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
+
+- **Warning**: the [mean absolute percentage error][mean-absolute-percentage-error] has several shortcomings:
+
+ - The measure is **not** suitable for intermittent demand patterns (i.e., when `a_i` is `0`).
+ - The [mean absolute percentage error][mean-absolute-percentage-error] is not symmetrical, as the measure cannot exceed 100% for forecasts which are too "low" and has no limit for forecasts which are too "high".
+ - When used to compare the accuracy of forecast models (e.g., predicting demand), the measure is biased toward forecasts which are too low.
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var incrnanmape = require( '@stdlib/stats/incr/nanmape' );
+
+var accumulator;
+var v1;
+var v2;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnanmape();
+
+// For each simulated datum, update the mean absolute percentage error...
+console.log( '\nValue\tValue\tMAPE\n' );
+for ( i = 0; i < 100; i++ ) {
+ v1 = ( randu() < 0.2 ) ? NaN : randu() * 100.0;
+ v2 = ( randu() < 0.2 ) ? NaN : randu() * 100.0;
+ accumulator( v1, v2 );
+}
+console.log( '\nFinal MAPE: %d\n', accumulator() );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+[mean-absolute-percentage-error]: https://en.wikipedia.org/wiki/Mean_absolute_percentage_error
+
+
+
+[@stdlib/stats/incr/maape]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/maape
+
+[@stdlib/stats/incr/mae]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/mae
+
+[@stdlib/stats/incr/mean]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/mean
+
+[@stdlib/stats/incr/mmape]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/mmape
+
+
+
+
+
+
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/incr/nanmape/benchmark/benchmark.js
new file mode 100644
index 000000000000..0907f47d778b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/benchmark/benchmark.js
@@ -0,0 +1,68 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var pkg = require( './../package.json' ).name;
+var incrnanmape = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var f;
+ var i;
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ f = incrnanmape();
+ if ( typeof f !== 'function' ) {
+ b.fail( 'should return a function' );
+ }
+ }
+ b.toc();
+ if ( typeof f !== 'function' ) {
+ b.fail( 'should return a function' );
+ }
+ b.pass( 'benchmark finished' );
+ b.end();
+});
+
+bench( pkg+'::accumulator', function benchmark( b ) {
+ var acc;
+ var v;
+ var i;
+
+ acc = incrnanmape();
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ v = acc( i+0.5, i+0.5 );
+ if ( v !== v ) {
+ b.fail( 'should not return NaN' );
+ }
+ }
+ b.toc();
+ if ( v !== v ) {
+ b.fail( 'should not return NaN' );
+ }
+ b.pass( 'benchmark finished' );
+ b.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/docs/img/equation_mean_absolute_percentage_error.svg b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/img/equation_mean_absolute_percentage_error.svg
new file mode 100644
index 000000000000..9367280b2aae
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/img/equation_mean_absolute_percentage_error.svg
@@ -0,0 +1,87 @@
+
\ No newline at end of file
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/docs/repl.txt b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/repl.txt
new file mode 100644
index 000000000000..7c7d0592dc50
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/repl.txt
@@ -0,0 +1,31 @@
+
+{{alias}}()
+ Returns an accumulator function which incrementally computes the mean
+ absolute percentage error (MAPE), ignoring `NaN` values.
+
+ If provided input values, the accumulator function returns an updated mean
+ absolute percentage error. If not provided input values, the accumulator
+ function returns the current mean absolute percentage error.
+
+ Returns
+ -------
+ acc: Function
+ Accumulator function.
+
+ Examples
+ --------
+ > var accumulator = {{alias}}();
+ > var m = accumulator()
+ null
+ > m = accumulator( 2.0, 3.0 )
+ ~33.33
+ > m = accumulator( 5.0, 2.0 )
+ ~91.67
+ > m = accumulator( 5.0, NaN )
+ ~91.67
+ > m = accumulator()
+ ~91.67
+
+ See Also
+ --------
+
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/index.d.ts
new file mode 100644
index 000000000000..d95333c3d127
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/index.d.ts
@@ -0,0 +1,70 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+// TypeScript Version: 4.1
+
+///
+
+/**
+* If provided input values, the accumulator function returns an updated mean absolute percentage error. If not provided input values, the accumulator function returns the current mean absolute percentage error.
+*
+* ## Notes
+*
+* - If provided `NaN`, it simply ignores that input.
+*
+* @param f - input value
+* @param a - input value
+* @returns mean absolute percentage error or null
+*/
+type accumulator = ( f?: number, a?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes the mean absolute percentage error.
+*
+* @returns accumulator function
+*
+* @example
+* var accumulator = incrnanmape();
+*
+* var m = accumulator();
+* // returns null
+*
+* m = accumulator( 2.0, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( NaN, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( 2.0, NaN );
+* // returns ~33.33
+*
+* m = accumulator( NaN, NaN );
+* // returns ~33.33
+*
+* m = accumulator( 5.0, 2.0 );
+* // returns ~91.67
+*
+* m = accumulator();
+* // returns ~91.67
+*/
+declare function incrnanmape(): accumulator;
+
+
+// EXPORTS //
+
+export = incrnanmape;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/test.ts b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/test.ts
new file mode 100644
index 000000000000..504affcb43ec
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/docs/types/test.ts
@@ -0,0 +1,73 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+import incrnanmape = require( './index' );
+
+
+// TESTS //
+
+// The function returns an accumulator function...
+{
+ incrnanmape(); // $ExpectType accumulator
+}
+
+// The compiler throws an error if the function is provided arguments...
+{
+ incrnanmape( '5' ); // $ExpectError
+ incrnanmape( 5 ); // $ExpectError
+ incrnanmape( true ); // $ExpectError
+ incrnanmape( false ); // $ExpectError
+ incrnanmape( null ); // $ExpectError
+ incrnanmape( undefined ); // $ExpectError
+ incrnanmape( [] ); // $ExpectError
+ incrnanmape( {} ); // $ExpectError
+ incrnanmape( ( x: number ): number => x ); // $ExpectError
+}
+
+// The function returns an accumulator function which returns an accumulated result...
+{
+ const acc = incrnanmape();
+
+ acc(); // $ExpectType number | null
+ acc( 3.14, 2.0 ); // $ExpectType number | null
+ acc( NaN, 2.0 ); // $ExpectType number | null
+ acc( 3.14, NaN ); // $ExpectType number | null
+ acc( NaN, NaN ); // $ExpectType number | null
+
+}
+
+// The compiler throws an error if the returned accumulator function is provided invalid arguments...
+{
+ const acc = incrnanmape();
+
+ acc( '5', 2.0 ); // $ExpectError
+ acc( true, 2.0 ); // $ExpectError
+ acc( false, 2.0 ); // $ExpectError
+ acc( null, 2.0 ); // $ExpectError
+ acc( [], 2.0 ); // $ExpectError
+ acc( {}, 2.0 ); // $ExpectError
+ acc( ( x: number ): number => x, 2.0 ); // $ExpectError
+
+ acc( 3.14, '5' ); // $ExpectError
+ acc( 3.14, true ); // $ExpectError
+ acc( 3.14, false ); // $ExpectError
+ acc( 3.14, null ); // $ExpectError
+ acc( 3.14, [] ); // $ExpectError
+ acc( 3.14, {} ); // $ExpectError
+ acc( 3.14, ( x: number ): number => x ); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/examples/index.js b/lib/node_modules/@stdlib/stats/incr/nanmape/examples/index.js
new file mode 100644
index 000000000000..6850aef8feab
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/examples/index.js
@@ -0,0 +1,43 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+'use strict';
+
+var randu = require( '@stdlib/random/base/randu' );
+var incrnanmape = require( './../lib' );
+
+var accumulator;
+var err;
+var v1;
+var v2;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnanmape();
+
+// For each simulated datum, update the mean absolute percentage error...
+console.log( '\nValue\tValue\tMAPE\n' );
+for ( i = 0; i < 100; i++ ) {
+ v1 = ( randu() < 0.2 ) ? NaN : randu() * 100.0;
+ v2 = ( randu() < 0.2 ) ? NaN : randu() * 100.0;
+ err = accumulator( v1, v2 );
+ if ( err !== null ) {
+ console.log( '%d\t%d\t%d', v1.toFixed( 3 ), v2.toFixed( 3 ), err.toFixed( 3 ) );
+ }
+}
+console.log( '\nFinal MAPE: %d\n', accumulator() );
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/lib/index.js b/lib/node_modules/@stdlib/stats/incr/nanmape/lib/index.js
new file mode 100644
index 000000000000..038f08ff28b9
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/lib/index.js
@@ -0,0 +1,54 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+'use strict';
+
+/**
+* Compute the mean absolute percentage error incrementally, ignoring `NaN`.
+*
+* @module @stdlib/stats/incr/nanmape
+*
+* @example
+* var incrnanmape = require( '@stdlib/stats/incr/nanmape' );
+*
+* var accumulator = incrnanmape();
+*
+* var m = accumulator();
+* // returns null
+*
+* m = accumulator( 2.0, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( NaN, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( 5.0, 2.0 );
+* // returns ~91.67
+*
+* m = accumulator();
+* // returns ~91.67
+*/
+
+// MODULES //
+
+var main = require( './main.js' );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/lib/main.js b/lib/node_modules/@stdlib/stats/incr/nanmape/lib/main.js
new file mode 100644
index 000000000000..40d9d45ffff1
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/lib/main.js
@@ -0,0 +1,81 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+'use strict';
+
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var incrmape = require( '@stdlib/stats/incr/mape' );
+
+
+// MAIN //
+
+/**
+* Returns an accumulator function which incrementally computes the mean absolute percentage error, ignoring `NaN` values.
+*
+* @returns {Function} accumulator function
+*
+* @example
+* var accumulator = incrnanmape();
+*
+* var m = accumulator();
+* // returns null
+*
+* m = accumulator( 2.0, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( NaN, 3.0 );
+* // returns ~33.33
+*
+* m = accumulator( 2.0, NaN );
+* // returns ~33.33
+*
+* m = accumulator( 5.0, 2.0 );
+* // returns ~91.67
+*
+* m = accumulator();
+* // returns ~91.67
+*/
+function incrnanmape() {
+ var acc = incrmape();
+ return accumulator;
+
+ /**
+ * If provided input values, the accumulator function returns an updated mean absolute percentage error. If not provided input values, the accumulator function returns the current mean absolute percentage error.
+ *
+ * @private
+ * @param {number} [f] - input value
+ * @param {number} [a] - input value
+ * @returns {(number|null)} mean absolute percentage error or null
+ */
+ function accumulator( f, a ) {
+ if ( arguments.length === 0 ) {
+ return acc();
+ }
+ if ( isnan( f ) || isnan( a ) ) {
+ return acc();
+ }
+ return acc( f, a );
+ }
+}
+
+
+// EXPORTS //
+
+module.exports = incrnanmape;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/package.json b/lib/node_modules/@stdlib/stats/incr/nanmape/package.json
new file mode 100644
index 000000000000..8cf605d7437e
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/package.json
@@ -0,0 +1,81 @@
+{
+ "name": "@stdlib/stats/incr/nanmape",
+ "version": "0.0.0",
+ "description": "Compute the mean absolute percentage error (MAPE) incrementally.",
+ "license": "Apache-2.0",
+ "author": {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ },
+ "contributors": [
+ {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ }
+ ],
+ "main": "./lib",
+ "directories": {
+ "benchmark": "./benchmark",
+ "doc": "./docs",
+ "example": "./examples",
+ "lib": "./lib",
+ "test": "./test"
+ },
+ "types": "./docs/types",
+ "scripts": {},
+ "homepage": "https://github.com/stdlib-js/stdlib",
+ "repository": {
+ "type": "git",
+ "url": "git://github.com/stdlib-js/stdlib.git"
+ },
+ "bugs": {
+ "url": "https://github.com/stdlib-js/stdlib/issues"
+ },
+ "dependencies": {},
+ "devDependencies": {},
+ "engines": {
+ "node": ">=0.10.0",
+ "npm": ">2.7.0"
+ },
+ "os": [
+ "aix",
+ "darwin",
+ "freebsd",
+ "linux",
+ "macos",
+ "openbsd",
+ "sunos",
+ "win32",
+ "windows"
+ ],
+ "keywords": [
+ "stdlib",
+ "stdmath",
+ "statistics",
+ "stats",
+ "mathematics",
+ "math",
+ "average",
+ "avg",
+ "mean",
+ "arithmetic mean",
+ "error",
+ "err",
+ "absolute",
+ "abs",
+ "percentage",
+ "percent",
+ "mape",
+ "deviation",
+ "difference",
+ "diff",
+ "delta",
+ "incremental",
+ "accumulator",
+ "time series",
+ "timeseries",
+ "demand",
+ "forecasting",
+ "forecast"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/incr/nanmape/test/test.js b/lib/node_modules/@stdlib/stats/incr/nanmape/test/test.js
new file mode 100644
index 000000000000..2b7db6560496
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanmape/test/test.js
@@ -0,0 +1,155 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var incrnanmape = require( './../lib' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof incrnanmape, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'the function returns an accumulator function', function test( t ) {
+ t.strictEqual( typeof incrnanmape(), 'function', 'returns expected value' );
+ t.end();
+});
+
+tape( 'the initial accumulated value is `null`', function test( t ) {
+ var acc = incrnanmape();
+ t.strictEqual( acc(), null, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the accumulator function incrementally computes the mean absolute percentage error', function test( t ) {
+ var expected;
+ var actual;
+ var delta;
+ var data;
+ var acc;
+ var sum;
+ var tol;
+ var N;
+ var x;
+ var y;
+ var i;
+
+ data = [
+ [ 2.0, 3.0 ],
+ [ 3.0, 1.0 ],
+ [ 2.0, 5.0 ],
+ [ 4.0, 4.0 ],
+ [ 3.0, 10.0 ],
+ [ 4.0, 5.0 ]
+ ];
+ N = data.length;
+
+ acc = incrnanmape();
+
+ sum = 0;
+ for ( i = 0; i < N; i++ ) {
+ x = data[ i ][ 0 ];
+ y = data[ i ][ 1 ];
+ sum += abs( ( y-x ) / y );
+ expected = 100.0 * ( sum/(i+1) );
+ actual = acc( x, y );
+ if ( actual === expected ) {
+ t.strictEqual( actual, expected, 'returns expected value' );
+ } else {
+ delta = abs( expected - actual );
+ tol = 1.0 * EPS * abs( expected );
+ t.strictEqual( delta <= tol, true, 'within tolerance. Actual: '+actual+'. Expected: '+expected+'. Delta: '+delta+'. Tol: '+tol+'.' );
+ }
+ }
+ t.end();
+});
+
+tape( 'if provided `NaN`, the value is ignored', function test( t ) {
+ var expected;
+ var actual;
+ var delta;
+ var data;
+ var tol;
+ var acc;
+ var i;
+
+ acc = incrnanmape();
+
+ data = [
+ [ 2.0, 3.0 ],
+ [ NaN, 3.0 ],
+ [ 2.0, NaN ],
+ [ NaN, NaN ],
+ [ 5.0, 2.0 ]
+ ];
+
+ expected = [
+ 100.0 * ( 1.0/3.0 ),
+ 100.0 * ( 1.0/3.0 ),
+ 100.0 * ( 1.0/3.0 ),
+ 100.0 * ( 1.0/3.0 ),
+ 100.0 * ( ( (1.0/3.0) + 1.5 ) / 2.0 )
+ ];
+
+ for ( i = 0; i < data.length; i++ ) {
+ actual = acc( data[ i ][ 0 ], data[ i ][ 1 ] );
+ if ( actual === expected[ i ] ) {
+ t.strictEqual( actual, expected[ i ], 'returns expected value');
+ } else {
+ delta = abs( actual - expected[ i ] );
+ tol = 1.0 * EPS * abs( expected[ i ] );
+ t.strictEqual( delta <= tol, true, 'within tolerance. Actual: '+actual+'. Expected: '+expected[ i ]+'. Delta: '+delta+'. Tol: '+tol+'.' );
+ }
+ }
+ t.end();
+});
+
+tape( 'if not provided an input value, the accumulator function returns the current mean absolute percentage error', function test( t ) {
+ var expected;
+ var actual;
+ var delta;
+ var data;
+ var acc;
+ var tol;
+ var i;
+
+ data = [
+ [ 2.0, 3.0 ],
+ [ 3.0, 5.0 ],
+ [ 10.0, 1.0 ]
+ ];
+ acc = incrnanmape();
+ for ( i = 0; i < data.length; i++ ) {
+ acc( data[ i ][ 0 ], data[ i ][ 1 ] );
+ }
+ actual = acc();
+ expected = 100.0 / 3.0 * ((1.0/3.0) + (2.0/5.0) + (9.0/1.0));
+ delta = abs( expected - actual );
+ tol = 1.0 * EPS * abs( expected );
+ t.strictEqual( delta <= tol, true, 'within tolerance. Actual: '+actual+'. Expected: '+expected+'. Delta: '+delta+'. Tol: '+tol+'.' );
+ t.end();
+});