Inital commit for pull

src/core/operations/Arithmetic.js

@@ -21,7 +21,15 @@ const Arithmetic = {
      * @constant
      * @default
      */
-    OPERATIONS: ["Sum", "Sub", "Multiply", "Divide", "Mean", "Median", "Mode"],
+    OPERATIONS: [
+        "Sum",
+        "Sub",
+        "Multiply",
+        "Divide",
+        "Mean",
+        "Median",
+        "Standard Deviation"
+    ],
 
     /**
      *
@@ -39,17 +47,17 @@ const Arithmetic = {
             if (splitNumbers[i].indexOf(".") >= 0) {
                 num = parseFloat(splitNumbers[i].trim());
             } else {
-                num = parseInt(splitNumbers[i].trim(), 10);
+                num = parseInt(splitNumbers[i].trim(), 0);
             }
-            if (num !== "NaN") {
+            if (!isNaN(num)) {
-                numbers.append(num);
+                numbers.push(num);
             }
         }
         num = Arithmetic.opMap[args[1] || "Sum"](numbers);
-        if (num !== null) {
+        if (num === null) {
-            return "The values " + args[1] + "equal: " + num;
+            return "";
         }
-        throw "Error with Arithmetic Operation: " + args[1];
+        return num;
     },
 
 
@@ -61,11 +69,11 @@ const Arithmetic = {
      * @returns {number}
      */
     _sum: function(data) {
-        let total = 0;
+        if (data.length > 0) {
-        for (let i = 0; i < data.length; i++) {
+            return data.reduce((acc, curr) => acc + curr);
-            total += data[i];
+        } else {
+            return null;
         }
-        return total;
     },
 
     /**
@@ -76,16 +84,11 @@ const Arithmetic = {
      * @returns {number}
      */
     _sub: function(data) {
-        let total = 0;
+        if (data.length > 0) {
-        if (data.length > 1) {
+            return data.reduce((acc, curr) => acc - curr);
-            total = data[0];
-            for (let i = 1; i < data.length; i++) {
-                total -= data[i];
-            }
         } else {
-            total = null;
+            return null;
         }
-        return total;
     },
 
     /**
@@ -96,16 +99,11 @@ const Arithmetic = {
      * @returns {number}
      */
     _multiply: function(data) {
-        let total = 0;
+        if (data.length > 0) {
-        if (data.length > 1) {
+            return data.reduce((acc, curr) => acc * curr);
-            total = data[0];
-            for (let i = 1; i < data.length; i++) {
-                total *= data[i];
-            }
         } else {
-            total = null;
+            return null;
         }
-        return total;
     },
 
     /**
@@ -116,16 +114,11 @@ const Arithmetic = {
      * @returns {number}
      */
     _divide: function(data) {
-        let total = 0;
+        if (data.length > 0) {
-        if (data.length > 1) {
+            return data.reduce((acc, curr) => acc / curr);
-            total = data[0];
-            for (let i = 1; i < data.length; i++) {
-                total /= data[i];
-            }
         } else {
-            total = null;
+            return null;
         }
-        return total;
     },
 
     /**
@@ -136,27 +129,82 @@ const Arithmetic = {
      * @returns {number}
      */
     _mean: function(data) {
-        let total = 0;
+        if (data.length > 0) {
-        if (data.length > 1) {
+            return Arithmetic._sum(data) / data.length;
-            total = Arithmetic._sum(data) / data.length;
         } else {
-            total = null;
+            return null;
+        }
+    },
+
+    /**
+     * Finds the median of a number array and returns the value.
+     *
+     * @private
+     * @param {number[]} data
+     * @returns {number}
+     */
+    _median: function (data) {
+        if ((data.length % 2) === 0) {
+            let first, second;
+            data.sort(function(a, b){
+                return a - b;
+            });
+            first = data[Math.floor(data.length / 2)];
+            second = data[Math.floor(data.length / 2) - 1];
+            return Arithmetic._mean([first, second]);
+        } else {
+            return data[Math.floor(data.length / 2)];
+        }
+    },
+
+    /**
+     * Finds the standard deviation of a number array and returns the value.
+     *
+     * @private
+     * @param {number[]} data
+     * @returns {number}
+     */
+    _stdDev: function (data) {
+        if (data.length > 0) {
+            let avg = Arithmetic._mean(data);
+            let devSum = 0;
+            for (let i = 0; i < data.length; i++) {
+                devSum += (data[i] - avg) ** 2;
+            }
+            return Math.sqrt(devSum / data.length);
+        } else {
+            return null;
         }
-        return total;
     },
 
     /**
      * A mapping of operation names to their function.
+     *
      * @constant
      */
     opMap: {
-        "Sum": function(numArray) { return Arithmetic._sum(numArray); },
+        "Sum": function(numArray) {
-        "Sub": function(numArray) { return Arithmetic._sub(numArray); },
+            return Arithmetic._sum(numArray);
-        "Multiply": function(numArray) { return Arithmetic._multiply(numArray); },
+        },
-        "Divide": function(numArray) { return Arithmetic._divide(numArray); },
+        "Sub": function(numArray) {
-        "Mean": function(numArray) { return Arithmetic._mean(numArray); },
+            return Arithmetic._sub(numArray);
+        },
+        "Multiply": function(numArray) {
+            return Arithmetic._multiply(numArray);
+        },
+        "Divide": function(numArray) {
+            return Arithmetic._divide(numArray);
+        },
+        "Mean": function(numArray) {
+            return Arithmetic._mean(numArray);
+        },
+        "Median": function(numArray) {
+            return Arithmetic._median(numArray);
+        },
+        "Standard Deviation": function (numArray) {
+            return Arithmetic._stdDev(numArray);
+        },
     },
-
 };
 
 export default Arithmetic;