summary - npm Package Compare versions

Comparing version 1.0.0 to 2.0.0

package.json

 {
   "name": "summary",
   "description": "Takes an array of numbers and calculates some descriptive statistics",
-  "version": "1.0.0",
+  "version": "2.0.0",
   "author": "Andreas Madsen <[e-mail]>",
@@ -26,5 +26,5 @@ "main": "./summary.js",
   "devDependencies": {
-    "tap": "0.6.x"
+    "tap": "~14.0.0"
   },
   "license": "MIT"
 }

summary.js

@@ -0,6 +1,6 @@
+'use strict';
 
-var array_types = [
-    Array, Int8Array, Uint8Array, Int16Array, Uint16Array,
-    Int32Array, Uint32Array, Float32Array, Float64Array
-];
+function isArray(x) {
+  return Array.isArray(x) || ArrayBuffer.isView(x) && !(x instanceof DataView);
+}
 
@@ -10,3 +10,3 @@ function Summary(data, sorted) {
 
-  if (array_types.indexOf(data.constructor) === -1) {
+  if (!isArray(data)) {
     throw TypeError('data must be an array');
@@ -54,4 +54,4 @@ }
   if (this._cache_sum === null) {
-    var sum = 0;
-    for (var i = 0; i < this._length; i++) sum += this._data[i];
+    let sum = 0;
+    for (let i = 0; i < this._length; i++) sum += this._data[i];
     this._cache_sum = sum;
@@ -65,11 +65,11 @@ }
   if (this._cache_mode === null) {
-    var data = this.sort();
+    const data = this.sort();
 
-    var modeValue = NaN;
-    var modeCount = 0;
-    var currValue = data[0];
-    var currCount = 1;
+    let modeValue = NaN;
+    let modeCount = 0;
+    let currValue = data[0];
+    let currCount = 1;
 
     // Count the amount of repeat and update mode variables
-    for (var i = 1; i < this._length; i++) {
+    for (let i = 1; i < this._length; i++) {
       if (data[i] === currValue) {
@@ -102,3 +102,8 @@ currCount += 1;
   if (this._cache_mean === null) {
-    this._cache_mean = this.sum() / this._length;
+    // Numerically stable mean algorithm
+    let mean = 0;
+    for (let i = 0; i < this._length; i++) {
+        mean += (this._data[i] - mean) / (i+1);
+    }
+    this._cache_mean = mean;
   }
@@ -111,5 +116,5 @@
   if (!this._cache_quartiles.hasOwnProperty(prob)) {
-    var data = this.sort();
-    var product = prob * this.size();
-    var ceil = Math.ceil(product);
+    const data = this.sort();
+    const product = prob * this.size();
+    const ceil = Math.ceil(product);
 
@@ -138,9 +143,13 @@ if (ceil === product) {
   if (this._cache_variance === null) {
-    var mean = this.mean();
-    var sqsum = 0;
-    for (var i = 0; i < this._length; i++) {
-      sqsum += (this._data[i] - mean) * (this._data[i] - mean);
+    // Numerically stable variance algorithm
+    const mean = this.mean();
+    let biasedVariance = 0;
+    for (let i = 0; i < this._length; i++) {
+      const diff = this._data[i] - mean;
+      biasedVariance += (diff * diff - biasedVariance) / (i+1);
     }
 
-    this._cache_variance = sqsum / (this._length - 1);
+    // Debias the variance
+    const debiasTerm = ((this._length) / (this._length - 1));
+    this._cache_variance = biasedVariance * debiasTerm;
   }
@@ -147,0 +156,0 @@

test.js

@@ -15,3 +15,3 @@
 test('testing sort method', function (t) {
-  const data = [2, 3, 7, -2, 0, 1, 1]
+  const data = [2, 3, 7, -2, 0, 1, 1];
 
@@ -39,2 +39,11 @@ t.deepEqual(
 
+test('testing sort method when cached', function (t) {
+  const s = summary([2, 3, 7, -2, 0, 1, 1]);
+
+  t.deepEqual(s.sort(), [-2, 0, 1, 1, 2, 3, 7]);
+  t.deepEqual(s.sort(), [-2, 0, 1, 1, 2, 3, 7]);
+
+  t.end();
+});
+
 test('testing size method', function (t) {
@@ -58,2 +67,9 @@ t.equal(
 
+test('testing sum method when cached', function (t) {
+  const s = summary([1, 10]);
+  t.equal(s.sum(), 11);
+  t.equal(s.sum(), 11);
+  t.end();
+});
+
 test('testing mode method', function (t) {
@@ -71,2 +87,17 @@ t.equal(
   t.equal(
+    summary([1, 2, 2, 3, 3, 3, 4]).mode(),
+    3
+  );
+
+  t.equal(
+    summary([1, 2, 2, 3, 3, 4]).mode(),
+    3
+  );
+
+  t.equal(
+    summary([1, 2, 2, 2, 3, 3, 4]).mode(),
+    2
+  );
+
+  t.equal(
     summary([1, 2, 3]).mode(),
@@ -79,2 +110,9 @@ 3
 
+test('testing mode method when cached', function (t) {
+  const s = summary([1, 2, 3]);
+  t.equal(s.mode(), 3);
+  t.equal(s.mode(), 3);
+  t.end();
+});
+
 test('testing mean method', function (t) {
@@ -89,2 +127,9 @@ t.equal(
 
+test('testing mean method when cached', function (t) {
+  const s = summary([2, 4]);
+  t.equal(s.mean(), 3);
+  t.equal(s.mean(), 3);
+  t.end();
+});
+
 test('testing quartile method', function (t) {
@@ -107,2 +152,13 @@ var data = summary([
 
+  // when cached
+  t.equal(data.quartile(0.00), 2.00);
+  t.equal(data.quartile(0.13), 3.00);
+  t.equal(data.quartile(0.26), 7.00);
+  t.equal(data.quartile(0.39), 14.0);
+  t.equal(data.quartile(0.52), 18.0);
+  t.equal(data.quartile(0.65), 21.0);
+  t.equal(data.quartile(0.78), 25.0);
+  t.equal(data.quartile(0.91), 28.0);
+  t.equal(data.quartile(1.00), 29.0);
+
   t.end();
@@ -119,2 +175,4 @@ });
   t.equal(data.median(), 18);
+  // when cached
+  t.equal(data.median(), 18);
 
@@ -124,2 +182,3 @@ t.end();
 
+
 test('testing variance method', function (t) {
@@ -131,2 +190,10 @@ t.equal(summary([-2, -1, 0, 1, 2]).variance(), 2.5);
 
+
+test('testing variance method when cached', function (t) {
+  const s = summary([-2, -1, 0, 1, 2]);
+  t.equal(s.variance(), 2.5);
+  t.equal(s.variance(), 2.5);
+  t.end();
+});
+
 test('testing sd method', function (t) {
@@ -138,2 +205,10 @@ t.equal(summary([-2, -1, 0, 1, 2]).sd(), Math.sqrt(2.5));
 
+test('testing sd method when cached', function (t) {
+  const s = summary([-2, -1, 0, 1, 2]);
+  t.equal(s.sd(), Math.sqrt(2.5));
+  t.equal(s.sd(), Math.sqrt(2.5));
+
+  t.end();
+});
+
 test('testing max method', function (t) {
@@ -145,2 +220,10 @@ t.equal(summary([6, 10, 2, 5]).max(), 10);
 
+test('testing max method when cached', function (t) {
+  const s = summary([6, 10, 2, 5]);
+  t.equal(s.max(), 10);
+  t.equal(s.max(), 10);
+
+  t.end();
+});
+
 test('testing min method', function (t) {
@@ -152,2 +235,10 @@ t.equal(summary([6, 10, 2, 5]).min(), 2);
 
+test('testing min method when cached', function (t) {
+  const s = summary([6, 10, 2, 5]);
+  t.equal(s.min(), 2);
+  t.equal(s.min(), 2);
+
+  t.end();
+});
+
 test('typed array', function (t) {
@@ -158,1 +249,7 @@ t.equal(summary(new Int8Array([2, 4])).mean(), 3);
 });
+
+test('not array', function (t) {
+  t.throws(() => summary({ length: 0 }), TypeError);
+
+  t.end();
+});

No alert changes

Improved metrics

Total package byte prevSize

13045

increased by21.43%

Lines of code

329

increased by34.84%

Worsened metrics

Number of package files

5

decreased by-16.67%

No dependency changes