London | 26-ITP-JAN | Asha Ahmed | Sprint 1 | Data Groups

Sprint-1/fix/median.js

@@ -6,8 +6,17 @@
 // 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];
+  if (!Array.isArray(list)) return null;
+  const num = list.filter((l) => typeof l === "number").sort((a, b) => a - b);
+  if (num.length < 1) return null;
+  if (num.length === 1) return num[0];
+
+  const middleIndex = Math.floor(num.length / 2);
+
+  if (num.length % 2 === 0) {
+    return (num[middleIndex] + num[middleIndex - 1]) / 2;
+  }
+  const median = num[middleIndex];
   return median;
 }
 

Sprint-1/fix/median.test.js

@@ -8,23 +8,33 @@ const calculateMedian = require("./median.js");
 
 describe("calculateMedian", () => {
   [
+    { input: [1.5, 2.5, 3.5], expected: 2.5 },
+    { input: [-2, -4, -6, -10], expected: -5 },
+    { input: [3, 3, 3, 3, 3], expected: 3 },
+    { input: [1, 3], expected: 2 },
+    { input: [1], expected: 1 },
     { input: [1, 2, 3], expected: 2 },
     { input: [1, 2, 3, 4, 5], expected: 3 },
     { 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))
   );
 
   [
+    { input: [-5, -1, -3], expected: -3 },
+    { input: [2, 2, 2, 2], expected: 2 },
+    { input: [8, 4], expected: 6 },
     { input: [3, 1, 2], expected: 2 },
     { input: [5, 1, 3, 4, 2], expected: 3 },
     { input: [4, 2, 1, 3], expected: 2.5 },
     { input: [6, 1, 5, 3, 2, 4], expected: 3.5 },
     { 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]", () => {
@@ -33,18 +43,29 @@ 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))
   );
 
   [
+    { input: ["a", null, 5, undefined], expected: 5 },
     { input: [1, 2, "3", null, undefined, 4], expected: 2 },
     { input: ["apple", 1, 2, 3, "banana", 4], expected: 2.5 },
     { input: [1, "2", 3, "4", 5], expected: 3 },
     { input: [1, "apple", 2, null, 3, undefined, 4], expected: 2.5 },
     { 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 +1,22 @@
-function dedupe() {}
+function dedupe(input) {
+  if (!Array.isArray(input)) {
+    return null;
+  }
+
+  if (input.length === 0) {
+    return [];
+  }
+
+  const newArray = [];
+
+  for (let i = 0; i < input.length; i++) {
+    const element = input[i];
+
+    if (!newArray.includes(element)) {
+      newArray.push(element);
+    }
+  }
+  return newArray;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,7 +16,6 @@ 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");
 
 // Given an array with no duplicates
 // When passed to the dedupe function
@@ -25,3 +24,33 @@ test.todo("given an empty array, it returns an empty array");
 // 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
+
+describe("dedupe", () => {
+  it("returns an empty array if passed an empty array", () =>
+    expect(dedupe([])).toEqual([]));
+
+  [
+    { input: [1, 2, 3], expected: [1, 2, 3] },
+    {
+      input: [4542543, 65756756, 433254],
+      expected: [4542543, 65756756, 433254],
+    },
+  ].forEach(({ input, expected }) =>
+    it(
+      "returns a copy of original array when passed array with no duplicates ",
+      () => expect(dedupe(input)).toEqual(expected),
+      expect(dedupe(input)).not.toBe(input)
+    )
+  );
+
+  [
+    { input: [1, 2, 3, "apple", 3, 2, {}], expected: [1, 2, 3, "apple", {}] },
+    {
+      input: [4542543, undefined, 4542543, 4542543, null, [], null],
+      expected: [4542543, undefined, null, []],
+    },
+  ].forEach(({ input, expected }) =>
+    it("returns array wit unique values in their first occurrence index when passed an array with numbers and non-number values ", () =>
+      expect(dedupe(input)).toEqual(expected))
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,9 @@
 function findMax(elements) {
+  const numberElements = elements.filter(
+    (el) => typeof el === "number" && !Number.isNaN(el)
+  );
+  if (numberElements.length === 0) return -Infinity;
+  return Math.max(...numberElements);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,94 @@ 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");
 
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
+describe("max()", () => {
+  it("returns -Infinity for empty array", () =>
+    expect(findMax([])).toBe(-Infinity));
 
-// Given an array with both positive and negative numbers
-// When passed to the max function
-// Then it should return the largest number overall
+  // Given an array with one number
+  // When passed to the max function
+  // Then it should return that number
 
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
+  [
+    { input: [43], expected: 43 },
+    { input: [342], expected: 342 },
+    { input: [65455453], expected: 65455453 },
+  ].forEach(({ input, expected }) =>
+    it("returns the only number in array with one number", () =>
+      expect(findMax(input)).toBe(expected))
+  );
 
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
+  // Given an array with both positive and negative numbers
+  // When passed to the max function
+  // Then it should return the largest number overall
 
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
+  [
+    { input: [43, -4], expected: 43 },
+    { input: [342, -45, -768, 23], expected: 342 },
+    { input: [65455453, -54666, -4566, 6565], expected: 65455453 },
+  ].forEach(({ input, expected }) =>
+    it("returns the largest number in array containing negative numbers", () =>
+      expect(findMax(input)).toBe(expected))
+  );
 
-// 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
+  // Given an array with just negative numbers
+  // When passed to the max function
+  // Then it should return the closest one to zero
+
+  [
+    { input: [-43, -4], expected: -4 },
+    { input: [-342, -45, -768, -23], expected: -23 },
+    { input: [-65455453, -54666, -4566, -6565], expected: -4566 },
+  ].forEach(({ input, expected }) =>
+    it("returns closes number to zero in an array with only negative numbers", () =>
+      expect(findMax(input)).toBe(expected))
+  );
+
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+
+  [
+    { input: [43.32, -4.1], expected: 43.32 },
+    { input: [342.54, -45.12, -768.76, 23.99], expected: 342.54 },
+    {
+      input: [65455453.4533, -54666.222, -4566.322, 6565.43],
+      expected: 65455453.4533,
+    },
+  ].forEach(({ input, expected }) =>
+    it("returns the largest decimal number in an array with numbers", () =>
+      expect(findMax(input)).toBe(expected))
+  );
+
+  // Given an array with non-number values
+  // When passed to the max function
+  // Then it should return the max and ignore non-numeric values
+
+  [
+    { input: [0, NaN, 1], expected: 1 },
+    { input: [1, 2, "3", null, undefined, NaN, 4], expected: 4 },
+    { input: ["apple", 1, 2, 34, "banana", 4], expected: 34 },
+    { input: [1, "2", 3, "4", 5], expected: 5 },
+    { input: [1, "apple", 2, null, 3, undefined, 4], expected: 4 },
+    { input: [3, "apple", 1, null, 2, undefined, 4, 54], expected: 54 },
+    { input: ["banana", 5, 3, "apple", 1, 4, 2], expected: 5 },
+  ].forEach(({ input, expected }) =>
+    it("returns max of numbers in an array containing non-numeric values", () =>
+      expect(findMax(input)).toEqual(expected))
+  );
+
+  // 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
+
+  [
+    ["not an array", "3", null, undefined],
+    ["apple", "banana"],
+    ["apple", null, undefined],
+    ["banana", {}],
+  ].forEach((input) =>
+    it("returns -Infinity in array with only non-numeric values", () =>
+      expect(findMax(input)).toBe(-Infinity))
+  );
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,22 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    return null;
+  }
+  // Check if array is empty
+  if (elements.length === 0) {
+    return 0;
+  }
+  // Filter only numeric values
+  const numericElements = elements.filter((item) => typeof item === "number");
+  if (numericElements.length === 0) {
+    return -Infinity;
+  }
+  // Calculate the sum of numeric values
+  let total = 0;
+  for (let i = 0; i < numericElements.length; i++) {
+    total += numericElements[i];
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,7 +13,6 @@ 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")
 
 // Given an array with just one number
 // When passed to the sum function
@@ -34,3 +33,11 @@ test.todo("given an empty array, returns 0")
 // 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(`Should return the correct sum of the numerical elements of an array`, () => {
+  expect(sum(["apple", "banana", 1, 10])).toEqual(11);
+  expect(sum([1, -1, -100])).toEqual(-100);
+  expect(sum([-10, -20, -3, -4])).toEqual(-37);
+  expect(sum([1.5, 10.5, 0.5])).toBeCloseTo(12.5);
+  expect(sum(["apple", "banana", "cherry"])).toEqual(-Infinity);
+});

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 (const element of list) {
     if (element === target) {
       return true;
     }