London | 25-ITP-Sep |Imran Mohamed | Sprint 1 | Sprint-1 exercises

Sprint-1/fix/median.js

@@ -6,9 +6,36 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  //check if its an array and has elements
+  if (!Array.isArray(list) || list.length === 0) {
+    return null;
+  }
+
+  //filter only numbers
+  const filteredList = list.filter(
+    (item) => typeof item === "number" && !isNaN(item)
+  );
+
+  //if no numbers present return null
+  if (filteredList.length === 0) {
+    return null;
+  }
+
+  //sort the filtered list
+  filteredList.sort((a, b) => a - b);
+
+  const isEven = filteredList.length % 2 === 0;
+
+  if (isEven) {
+    const mid1 = filteredList.length / 2 - 1;
+    const mid2 = mid1 + 1;
+    const median = (filteredList[mid1] + filteredList[mid2]) / 2;
+    return median;
+  } else {
+    const mid = Math.floor(filteredList.length / 2);
+    const median = filteredList[mid];
+    return median;
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/fix/median.test.js

@@ -13,7 +13,8 @@ describe("calculateMedian", () => {
     { input: [1, 2, 3, 4], expected: 2.5 },
     { input: [1, 2, 3, 4, 5, 6], expected: 3.5 },
   ].forEach(({ input, expected }) =>
-    it(`returns the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   [
@@ -24,7 +25,8 @@ describe("calculateMedian", () => {
     { input: [110, 20, 0], expected: 20 },
     { input: [6, -2, 2, 12, 14], expected: 6 },
   ].forEach(({ input, expected }) =>
-    it(`returns the correct median for unsorted array [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the correct median for unsorted array [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   it("doesn't modify the input array [3, 1, 2]", () => {
@@ -33,8 +35,17 @@ describe("calculateMedian", () => {
     expect(list).toEqual([3, 1, 2]);
   });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for non-numeric array (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +56,7 @@ describe("calculateMedian", () => {
     { input: [3, "apple", 1, null, 2, undefined, 4], expected: 2.5 },
     { input: ["banana", 5, 3, "apple", 1, 4, 2], expected: 3 },
   ].forEach(({ input, expected }) =>
-    it(`filters out non-numeric values and calculates the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`filters out non-numeric values and calculates the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,12 @@
-function dedupe() {}
+function dedupe(arr) {
+    if(!arr.length) return [];
+    const result = [];
+    arr.forEach(item => {
+        if(!result.includes(item)) {
+            result.push(item);
+        }
+    });
+    return result;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,4 +1,5 @@
-const dedupe = require("./dedupe.js");
+const dedupe = require("./dedupe");
+
 /*
 Dedupe Array
 
@@ -16,12 +17,25 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+test("given an empty array, it returns an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("given an array with no duplicates, it returns a copy of the original array", () => {
+  const arr = ["a", "b", "c"];
+  const result = dedupe(arr);
+  expect(result).toEqual(arr);
+  expect(result).not.toBe(arr);
+});
 
 // Given an array with strings or numbers
 // When passed to the dedupe function
-// Then it should remove the duplicate values, preserving the first occurence of each element
+// Then it should remove the duplicate values, preserving the first occurrence of each element
+test("given an array with strings or numbers, it removes duplicate values preserving the first occurrence of each element", () => {
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+  expect(dedupe([1, 1, 2, 2, 3, 1, 2, 4, 5, 5])).toEqual([1, 2, 3, 4, 5]);
+  expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,11 @@
-function findMax(elements) {
+function findMax(arr) {
+    let max = -Infinity;
+    for (let i = 0; i < arr.length; i++) {
+        if (typeof arr[i] === 'number' && arr[i] > max) {
+            max = arr[i];
+        }
+    }
+    return max;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,47 @@ const findMax = require("./max.js");
 // When passed to the max function
 // Then it should return -Infinity
 // Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+test("given an empty array, returns -Infinity", () => {
+  expect(findMax([])).toBe(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
-
+test("given an array with one number, returns that number", () => {
+  expect(findMax([42])).toBe(42);
+});
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("given an array with both positive and negative numbers, returns the largest number", () => {
+  expect(findMax([-1,0,5,20,-30])).toBe(20);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given an array with just negative numbers, returns the closest one to zero", () => {
+  expect(findMax([-10,-5,-1,-20])).toBe(-1);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given an array with decimal numbers, returns the largest decimal number", () => {
+  expect(findMax([1.5,22.5,0.75,20.13])).toBe(22.5);
+});
 
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
-
+test("given an array with non-number values, returns the max and ignores non-numeric values", () => {
+  expect(findMax([10,"hello",20,"100"])).toBe(20);
+}); 
 // Given an array with only non-number values
 // When passed to the max function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given an array with only non-number values, returns -Infinity", () => {
+  expect(findMax(["a","b","c","d"])).toBe(-Infinity);
+});
+

Sprint-1/implement/sum.js

@@ -1,4 +1,10 @@
-function sum(elements) {
+function sum(arr) {
+    return arr.reduce((acc, curr) => {
+        if (typeof curr === 'number') {
+            return acc + curr;
+        }
+        return acc;
+    }, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,41 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("given an empty array, returns 0",()=>{
+    expect(sum([])).toBe(0);
+})
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given an array with one number, returns that number",()=>{
+    expect(sum([20])).toBe(20);
+})
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given an array with negative numbers, returns correct sum",()=>{
+    expect(sum([-5,-10,-15])).toBe(-30);
+})
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given an array with decimal numbers, returns correct sum",()=>{
+    expect(sum([1.5,2.5,3.5])).toBeCloseTo(7.5, 5);
+})
 
 // Given an array containing non-number values
 // When passed to the sum function
 // Then it should ignore the non-numerical values and return the sum of the numerical elements
+test("given an array with non-number values, ignores them and returns correct sum",()=>{
+    expect(sum([10,'hello',20,['test'],30,{a:'a'}])).toBe(60);
+})
 
 // Given an array with only non-number values
 // When passed to the sum function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given an array with only non-number values, returns 0",()=>{
+    expect(sum(['hello','world',['test'],{a:'a'}])).toBe(0);
+})

Sprint-1/package.json

@@ -2,7 +2,7 @@
   "name": "week-1",
   "version": "1.0.0",
   "description": "This README will guide you through the different sections for this week.",
-  "main": "writers.js",
+  "main": "median.js",
   "scripts": {
     "test": "jest"
   },

Sprint-1/refactor/includes.js

@@ -1,8 +1,7 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
+  for (let element of list) {
     if (element === target) {
       return true;
     }