Manchester | 26-ITP-Jan | Mehroz Munir | Sprint 1 | Coursework exercises

Sprint-1/fix/median.js

@@ -6,8 +6,24 @@
 // 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];
+  let median = null;
+  //return null if the list is not an array
+  if (!Array.isArray(list)) return median;
+
+  // return null if none of the items in the array is a number
+  if (!list.some((item) => typeof item === "number")) return median;
+
+  let numericArray = list.filter((item) => typeof item === "number");
+  let sortedArray = numericArray.toSorted((a, b) => a - b);
+  const middleIndex = Math.floor(sortedArray.length / 2);
+
+  //check if the number of items in the array are even or odd
+  // and then calculate the median accordingly
+  if (sortedArray.length % 2 === 0)
+    median = (sortedArray[middleIndex - 1] + sortedArray[middleIndex]) / 2;
+  else median = sortedArray[middleIndex];
+
+  if (median === null) throw new Error("Median can't be null");
   return median;
 }
 

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 +1,7 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) throw new Error(arr + " is not an array");
+  else if (arr.length === 0) return arr;
+  else return Array.from(new Set(arr));
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -10,18 +10,49 @@ E.g. dedupe(['a','a','a','b','b','c']) target output: ['a','b','c']
 E.g. dedupe([5, 1, 1, 2, 3, 2, 5, 8]) target output: [5, 1, 2, 3, 8]
 E.g. dedupe([1, 2, 1]) target output: [1, 2]
 */
+describe("dedupe", () => {
+  // Given an empty array
+  // When passed to the dedupe function
+  // Then it should return an empty array
+  it("given an empty array it should return an empty array", () => {
+    const array = [];
+    dedupeArray = dedupe(array);
+    expect(dedupeArray).toEqual([]);
+  });
 
-// Acceptance Criteria:
+  // Given an array with no duplicates
+  // When passed to the dedupe function
+  // Then it should return a copy of the original array
+  [["a", "b", "c"], ["A", 1, "j", "?"], ["c"]].forEach((val) =>
+    it(`returns copy of the original array if there are no duplicates in [${val}]`, () =>
+      expect(dedupe(val)).toEqual(val))
+  );
+  // Given an array with strings or numbers
+  // When passed to the dedupe function
+  // Then it should remove the duplicate values, preserving the first occurrence of each element
+  [
+    { input: [1, 2, 1, 3, 1, 2, 10, 5, 0, 10], expected: [1, 2, 3, 10, 5, 0] },
+    { input: [1, 2, 1, 4], expected: [1, 2, 4] },
+    { input: [1, 1, 1, 1, 1], expected: [1] },
+    {
+      input: ["banana", "apple", "apple", "banana", "apple", "banana"],
+      expected: ["banana", "apple"],
+    },
+    {
+      input: [" ", "empty", "", " ", "", "empty"],
+      expected: [" ", "empty", ""],
+    },
+    { input: ["2", "2", "3", "1"], expected: ["2", "3", "1"] },
+  ].forEach(({ input, expected }) =>
+    it(`returns a copy of array removing the duplicates from [${input}]`, () =>
+      expect(dedupe(input)).toEqual(expected))
+  );
 
-// 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
-// Then it should return a copy of the original 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
+  // Given an input value that is not array could be null or undefined or just a number or string
+  // When passed to the dedupe function
+  // Then it should thrown an error
+  [null, 930, "just a string", undefined, {}].forEach((val) =>
+    it("throw an error if the input is not an array", () =>
+      expect(() => dedupe(val)).toThrow(val + " is not an array"))
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,7 @@
-function findMax(elements) {
+function findMax(array) {
+  if (!Array.isArray(array)) throw new Error(array + " is not an array");
+  let numbersArray = array.filter((value) => typeof value === "number");
+  return Math.max(...numbersArray);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -12,32 +12,104 @@ We have set things up already so that this file can see your function from the o
 
 const findMax = require("./max.js");
 
-// Given an empty array
-// 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
-
-// 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 just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
-
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
-
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
-
-// 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
+describe("findMax", () => {
+  // Given an empty array
+  // When passed to the max function
+  // Then it should return -Infinity
+  it("if an empty array is passed to the the findMax function, -Infinity should be returned", () => {
+    emptyArray = [];
+    expect(findMax(emptyArray)).toEqual(-Infinity);
+  });
+
+  // Given an array with one number
+  // When passed to the max function
+  // Then it should return that number
+  [[1], [70], [0], [-25], [100129]].forEach((val) =>
+    it(`When an array with only one number is passed i.e. [${val}], it should return that number`, () =>
+      expect(findMax(val)).toEqual(val[0]))
+  );
+
+  // Given an array with both positive and negative numbers
+  // When passed to the max function
+  // Then it should return the largest number overall
+  [
+    { input: [12, -2, 4, 6, 0], expected: 12 },
+    { input: [2, 5, 990, -4], expected: 990 },
+    { input: [0, -1, -5], expected: 0 },
+    { input: [0, -1, 300, 3], expected: 300 },
+  ].forEach(({ input, expected }) =>
+    it(`returns the max number from the array [${input}]`, () =>
+      expect(findMax(input)).toEqual(expected))
+  );
+
+  // Given an array with just negative numbers
+  // When passed to the max function
+  // Then it should return the closest one to zero
+  [
+    { input: [-4, -2, -1902, -2, -1], expected: -1 },
+    { input: [-9088, -9087, -990788, -4888777], expected: -9087 },
+    { input: [-1, -5], expected: -1 },
+  ].forEach(({ input, expected }) =>
+    it(`returns the max number from the array of negative numbers only [${input}]`, () =>
+      expect(findMax(input)).toEqual(expected))
+  );
+
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+  [
+    { input: [-4.2, 2.8, -19.8009, 2.4, 1.5], expected: 2.8 },
+    { input: [-90.88, 0.001, -990.788], expected: 0.001 },
+    { input: [-1.11, -5.3], expected: -1.11 },
+  ].forEach(({ input, expected }) =>
+    it(`returns the max number from the array of decimal numbers [${input}]`, () =>
+      expect(findMax(input)).toEqual(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: [-4, -2, "what is this", -1902, -2, "??", -1], expected: -1 },
+    {
+      input: [-9088, ".oi9e9", "1000000", -9087, 990788, -4888777],
+      expected: 990788,
+    },
+    { input: [-1.11, "here", -5.233, "ignore me please"], expected: -1.11 },
+  ].forEach(({ input, expected }) =>
+    it(`returns the max number from the array of numbers and non-numbers values [${input}]`, () =>
+      expect(findMax(input)).toEqual(expected))
+  );
+
+  // Given an array with only non-number values
+  // When passed to the max function
+  // Then it should return the least surprising value given how it behaves for all other inputs
+
+  /* Ans: If there is no number in the array than considering the behavior for the above inputs
+   the least surprising value in return would be -Infinity as our array has zero elements which are numbers*/
+  [
+    {
+      input: ["Not a number", "what is this", "least surprising", "??", "what"],
+      expected: -Infinity,
+    },
+    {
+      input: ["kkdkas", "Ahan!", "23"],
+      expected: -Infinity,
+    },
+    {
+      input: ["here", "Least surprising", "????", "vale is", "-Infinity"],
+      expected: -Infinity,
+    },
+  ].forEach(({ input, expected }) =>
+    it(`returns the least surprising value for only non-numbers array [${input}]`, () =>
+      expect(findMax(input)).toEqual(expected))
+  );
+
+  // Given an input that is not array could be null or undefined or just a number or string
+  // When passed to the findMax function
+  // Then it should thrown an error
+  [null, 930, "just a string", undefined, {}].forEach((val) =>
+    it("throw an error if the input is not an array", () =>
+      expect(() => findMax(val)).toThrow(val + " is not an array"))
+  );
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,12 @@
-function sum(elements) {
+function sum(array) {
+  if (!Array.isArray(array)) throw new Error(array + " is not an array");
+  let numbersArray = array.filter((value) => typeof value === "number");
+  let initialValue = 0;
+  let sum = numbersArray.reduce(
+    (accumulator, currentValue) => accumulator + currentValue,
+    initialValue
+  );
+  return sum;
 }
 
 module.exports = sum;