Sheffield | 25-ITP-Sep | Xiayidan Abuxuukuer | Sprint 1 | Coursework

Sprint-1/fix/median.js

@@ -5,10 +5,31 @@
 // Hint: Please consider scenarios when 'list' doesn't have numbers (the function is expected to return null)
 // 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;
+//}
+
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+
+  if(!Array.isArray(list)) return null;
+
+  const nums = list.filter(x => typeof x ==="number");
+
+  if(nums.length ===0) return null;
+
+  nums.sort((a, b) => a - b);
+
+  const mid = Math.floor(nums.length / 2);
+
+  if (nums.length % 2 ===1){
+
+    return nums[mid];
+  }
+  else{
+    return (nums[mid - 1] + nums[mid]) / 2; 
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/fix/median.test.js

@@ -7,44 +7,44 @@
 const calculateMedian = require("./median.js");
 
 describe("calculateMedian", () => {
-  [
-    { 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 median for sorted arrays", () =>{
+    expect(calculateMedian([1, 2, 3])).toBe(2);
+    expect(calculateMedian([1, 2, 3, 4, 5])).toBe(3);
+    expect(calculateMedian([1, 2, 3, 4])).toBe(2.5);
+    expect(calculateMedian([1, 2, 3, 4, 5, 6])).toBe(3.5);
+  });
 
-  [
-    { 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 median for unsorted arrays", () =>{
+    expect(calculateMedian([3, 1, 2])).toBe(2);
+    expect(calculateMedian([5, 1, 3, 4, 2])).toBe(3);
+    expect(calculateMedian([4, 2, 1, 3])).toBe(2.5);
+    expect(calculateMedian([6, 1, 5, 3, 2, 4])).toBe(3.5);
+    expect(calculateMedian([110, 20, 0])).toBe(20);
+    expect(calculateMedian([6, -2, 2, 12, 14])).toBe(6);
+  });
 
-  it("doesn't modify the input array [3, 1, 2]", () => {
-    const list = [3, 1, 2];
-    calculateMedian(list);
-    expect(list).toEqual([3, 1, 2]);
+  it("does not modify the original array", () => {
+    const arr = [3, 1, 2];
+    calculateMedian(arr);
+    expect(arr).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))
-  );
+  it("returns null for invalid or empty arrays", () =>{
+    expect(calculateMedian("not an array")).toBe(null);
+    expect(calculateMedian(123)).toBe(null);
+    expect(calculateMedian(null)).toBe(null);
+    expect(calculateMedian(undefined)).toBe(null);
+    expect(calculateMedian({})).toBe(null);
+    expect(calculateMedian([])).toBe(null);
+    expect(calculateMedian(["apple", null, undefined])).toBe(null);
+  });
 
-  [
-    { 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-numbers and returns correct median", () =>{
+    expect(calculateMedian([1, 2, "3", null, undefined, 4])).toBe(2);
+    expect(calculateMedian(["apple", 1, 2, 3, "banana", 4])).toBe(2.5);
+    expect(calculateMedian([1, "2", 3, "4", 5])).toBe(3);
+    expect(calculateMedian([1, "apple", 2, null, 3, undefined, 4])).toBe(2.5);
+    expect(calculateMedian([3, "apple", 1, null, 2, undefined, 4])).toBe(2.5);
+    expect(calculateMedian(["banana", 5, 3, "apple", 1, 4, 2])).toBe(3);
+  });
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,18 @@
-function dedupe() {}
+function dedupe(arr){
+
+    if (!Array.isArray(arr) || arr.length === 0) return [];
+
+    const result = [];
+
+    for (let i = 0; i < arr.length; i++){
+
+      if (!result.includes(arr[i])){
+
+        result.push(arr[i]);
+      }
+    }
+
+  return result;
+
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,32 @@ 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");
 
+describe("dedupe function", () =>{
+    it("returns an empty array for 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
 
+it("returns the same array if there are no duplicates", () =>{
+    expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+
+    expect(dedupe(["a", "b", "c"])).toEqual(["a", "b", "c"]);
+
+  });
 // 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
+
+it("removes duplicates and preserves first occurrence", () =>{
+
+    expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+    expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+    expect(dedupe(["a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+
+  });
+});

Sprint-1/implement/max.js

@@ -1,4 +1,19 @@
 function findMax(elements) {
-}
+    if (!Array.isArray(elements)) return -Infinity;
+
+    const numbers = elements.filter(x => typeof x ==="number");
+    if (numbers.length === 0) return -Infinity;
+
+    let max = numbers[0];
+    for (let i = 1; i < numbers.length; i++) {
+      if (numbers[i] > max) max = numbers[i];
+    }
+
+    return max;
+  }
+
+  console.log(findMax([10, 5, 30, 2])); 
+   console.log(findMax(['a', 10, 5]));
+    console.log(findMax([]));
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,52 @@ 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");
-
+describe("findMax function", () => {
+    // empty array
+    it("returns -Infinity for an empty array", () => {
+      expect(findMax([])).toBe(-Infinity);
+    });
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
 
+it("returns that number for a single-element array", () => {
+    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
 
+it("returns the largest number overall", () =>{
+    expect(findMax([-1, 0, 5, -10, 3])).toBe(5);
+  });
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
 
+it("returns the closest to zero for all negative numbers", () =>{
+    expect(findMax([-10, -3, -7])).toBe(-3);
+  });
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
 
+it("returns the largest decimal number", () => {
+    expect(findMax([1.1, 2.2, 1.5])).toBe(2.2);
+  });
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
 
+it("ignores non-numbers and returns the max", () => {
+    expect(findMax([1, "a", 5, null, 2])).toBe(5);
+  });
 // 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
+
+it("returns -Infinity if no numbers are present", () => {
+    expect(findMax(["a", null, "b"])).toBe(-Infinity);
+  });
+
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,22 @@
-function sum(elements) {
-}
+function sum(elements){
+
+    if (!Array.isArray(elements) || elements.length ===0) return 0;
+
+    const numbers = elements.filter(x => typeof x === "number");
+
+    let total =0;
+
+    for (let i =0; i< numbers.length; i++){
+
+      total += numbers[i];
+
+    }
+
+    return total;
+  }
+
+  console.log(sum([10, 20, 30]));
+   console.log(sum([1, "a", 2, null, 3]));
+   console.log(sum([])); 
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,67 @@ 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")
+
+describe("sum function", ()=>{
+    it("returns 0 for an empty array", () =>{
+
+      expect(sum([])).toBe(0);
+
+    });
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
 
+it("returns that number for a single-element array", ()=>{
+
+    expect(sum([42])).toBe(42);
+
+  });
+
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
 
+it("sums negative numbers correctly", ()=>{
+
+    expect(sum([-1, -2, -3])).toBe(-6);
+
+    expect(sum([5, -3, 2])).toBe(4);
+
+  });
+
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
 
+it("sums decimal numbers correctly", () =>{
+
+    expect(sum([1.5, 2.5, 3])).toBe(7);
+
+    expect(sum([0.1, 0.2, 0.3])).toBeCloseTo(0.6);
+
+  });
+
 // 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
 
+it("ignores non-numbers and sums only numerical elements", () =>{
+
+    expect(sum(["hi", 10, "hey", 20])).toBe(30);
+
+    expect(sum([1, "apple", 2, null, 3])).toBe(6);
+
+  });
+
 // 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
+
+it("returns 0 if there are no numerical elements", () =>{
+
+    expect(sum(["apple", null, undefined, "banana"])).toBe(0);
+
+  });
+});

Sprint-1/refactor/includes.js

@@ -1,9 +1,10 @@
 // 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];
-    if (element === target) {
+function includes(list, target){
+
+  for (const element of list){
+
+    if (element === target){
       return true;
     }
   }