GLASGOW | Jan-26-ITP | Prakash Dcosta | Sprint 1 | Data Groups

Sprint-1/fix/median.js

@@ -6,9 +6,29 @@
 // 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;
+  // It must be an array
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  // Keep only numeric values
+  const numbers = list.filter(
+    (value) => typeof value === "number" && !isNaN(value)
+  );
+
+  // If there are no numbers existing then return null
+  if (numbers.length === 0) return null;
+
+  // Sort numbers without modifying original list
+  const sorted = [...numbers].sort((a, b) => a - b);
+  const middle = Math.floor(sorted.length / 2);
+
+  // For even length
+  if (sorted.length % 2 === 0) {
+    return (sorted[middle - 1] + sorted[middle]) / 2;
+  }
+
+  // For odd length
+  return sorted[middle];
 }
 
 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))
   );
 
   [
@@ -24,17 +25,39 @@ 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]", () => {
     const list = [3, 1, 2];
     calculateMedian(list);
     expect(list).toEqual([3, 1, 2]);
   });
+  // Test for single number array
+  it("returns the value for a single-element array", () => {
+    expect(calculateMedian([5])).toBe(5);
+  });
+  // Test for only 1 numeric value in an array
+  it("returns the only numeric value in mixed array", () => {
+    expect(calculateMedian(["apple", 10, "banana"])).toBe(10);
+  });
+  // Test for decimal numbers only
+  it("works with decimal numbers", () => {
+    expect(calculateMedian([2.5, 3.5, 4.5])).toBe(3.5);
+  });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for invalid input (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +68,7 @@ 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 +1,4 @@
-function dedupe() {}
+function dedupe(arr) {
+  return [...new Set(arr)];
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,29 @@ 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("returns copy of the original array if there are no duplicates", () => {
+  const input = [10, 45, 85, 20];
+  const result = dedupe(input);
+  expect(result).toEqual(input);
+  expect(input).toEqual([10, 45, 85, 20]);
+  expect(result).not.toBe(input);
+});
 
 // 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
+test("returns first occurance for array of strings or numbers", () => {
+  expect(dedupe([10, 10, 20, 20, 30, 40])).toEqual([10, 20, 30, 40]);
+  expect(dedupe(["hello", "hello", "hi", "a", "hi"])).toEqual([
+    "hello",
+    "hi",
+    "a",
+  ]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,13 @@
-function findMax(elements) {
+function findMax(arr) {
+  if (!Array.isArray(arr)) return -Infinity;
+
+  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 +16,59 @@ 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([5])).toBe(5);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("returns the largest number overall", () => {
+  expect(findMax([-25, 3, 12, -32])).toBe(12);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("returns the closest number to zero", () => {
+  expect(findMax([-25, -345, -1, -72])).toBe(-1);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("returns the largest decimal number", () => {
+  expect(findMax([1.85, 2.563, 12.23, 0.24])).toBe(12.23);
+});
 
 // 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("returns max and ignores non number values", () => {
+  expect(findMax(["stay", "300", "quiet", -32, 5])).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
+test("returns infinity in non number values", () => {
+  expect(findMax(["hi", "sally", "a", "alpha"])).toBe(-Infinity);
+});
+// Given an array with null input
+// returns -Infinity for null input
+test("returns -Infinity where input is null", () => {
+  expect(findMax(null)).toBe(-Infinity);
+});
+
+// Given an array with undefined input
+// returns -Infinity for undefined input
+test("returns -Infinity where input is undefined", () => {
+  expect(findMax(undefined)).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,14 @@
-function sum(elements) {
+function sum(arr) {
+  let total = 0;
+  for (let i = 0; i < arr.length; i++) {
+    if (typeof arr[i] === "number" && !isNaN(arr[i])) {
+      total += arr[i];
+    }
+  }
+  return total;
 }
 
+let arr = [Infinity, -Infinity];
+console.log(sum(arr));
+
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,55 @@ 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("returns the same number when an array has just 1 number", () => {
+  expect(sum([8])).toBe(8);
+});
 
 // 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([-50, -20, 10])).toBe(-60);
+});
 // 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/float numbers, returns correct sum", () => {
+  expect(sum([2.8, 4.2, 7.7])).toBeCloseTo(14.7);
+});
 // 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, returns sum of numbers", () => {
+  expect(sum(["quiet", -20, "good", 10, 25])).toBe(15);
+});
 
 // 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("returns 0 foe non number values", () => {
+  expect(sum(["sally", "cousin", "hi", "a"])).toBe(0);
+});
+
+// Given an array with NaN and numbers
+// When passed to the sum function
+// Then it should ignore NaN and return the sum of the numbers
+test("should ignore NaN and return the correct sum", () => {
+  expect(sum([32, NaN, 25])).toEqual(57);
+  expect(sum([NaN, 1])).toEqual(1);
+  expect(sum([NaN, 0])).toEqual(0);
+});
+
+// Given an array with Infinity and -Infinity
+// When passed to the sum function
+// Then it should return NaN (standard JS behavior for infinite subtraction)
+test("should return NaN when summing Infinity and -Infinity", () => {
+  expect(sum([Infinity, -Infinity])).toBeNaN();
+});

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;
     }