London | ITP-MAY-25 | Surafel Workneh| Module: Data Groups | Sprint-1

Sprint-1/fix/median.js

@@ -1,14 +1,21 @@
-// Fix this implementation
-// Start by running the tests for this function
-// If you're in the Sprint-1 directory, you can run `npm test -- fix` to run the tests in the fix directory
+function calculateMedian(list) {
+  // Check if input is a valid array
+  if (!Array.isArray(list)) return null;
 
-// 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).
+  // Filter out only numeric values
+  const nums = list.filter(val => typeof val === 'number' && !isNaN(val));
+  if (nums.length === 0) return null;
 
-function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  // Clone and sort the array numerically
+  const sorted = [...nums].sort((a, b) => a - b);
+  const mid = Math.floor(sorted.length / 2);
+
+  // Return median based on even or odd length
+  if (sorted.length % 2 !== 0) {
+    return sorted[mid];
+  } else {
+    return (sorted[mid - 1] + sorted[mid]) / 2;
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,17 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) return [];
+
+  const seen = new Set();
+  const result = [];
+
+  for (const item of arr) {
+    if (!seen.has(item)) {
+      seen.add(item);
+      result.push(item);
+    }
+  }
+
+  return result;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,41 @@ 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.todo("given an empty array, it returns an empty array");
+  test("returns an empty array when given 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 of numbers with no duplicates, it returns a copy of the original array", () => {
+  const input = [1, 2, 3];
+  const result = dedupe(input);
+  expect(result).toEqual([1, 2, 3]);
+  expect(result).not.toBe(input); // Ensure it's a new array, not the same reference
+});
+
+test("given an array of strings with no duplicates, it returns a copy of the original array", () => {
+  const input = ["a", "b", "c"];
+  const result = dedupe(input);
+  expect(result).toEqual(["a", "b", "c"]);
+  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("removes duplicate numbers, preserving the 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]);
+});
+
+test("removes duplicate strings, preserving the first occurrence", () => {
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+  expect(dedupe(["x", "y", "x", "z", "y"])).toEqual(["x", "y", "z"]);
+});
+
+test("handles mixed types (strings and numbers)", () => {
+  expect(dedupe(["1", 1, "1", 2, 2, "2"])).toEqual(["1", 1, 2, "2"]);
+  expect(dedupe([1, "1", 1, "1"])).toEqual([1, "1"]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,11 @@
+
+
 function findMax(elements) {
+  if (!Array.isArray(elements)) return -Infinity;
+
+  const nums = elements.filter(val => typeof val === 'number' && !isNaN(val));
+
+  return nums.length > 0 ? Math.max(...nums) : -Infinity;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,48 @@ 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.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 positive and negative numbers, returns the largest", () => {
+  expect(findMax([-10, 5, 20, -3])).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 only negative numbers, returns the closest to zero", () => {
+  expect(findMax([-100, -20, -3, -50])).toBe(-3);
+});
 
 // 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", () => {
+  expect(findMax([1.2, 3.5, 2.9, 3.6])).toBe(3.6);
+});
 
 // 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 of valid numbers", () => {
+  expect(findMax(["a", 10, "b", 20, null, undefined, NaN, 5])).toBe(20);
+  expect(findMax([false, 3, true, 7, "hello"])).toBe(7);
+});
 
 // 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", null, undefined, NaN, {}, [], "b"])).toBe(-Infinity);
+  expect(findMax([false, true, "zero", "1", {}, []])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,9 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) return 0;
+
+  return elements.reduce((acc, val) => {
+    return typeof val === "number" && !isNaN(val) ? acc + val : acc;
+  }, 0);
 }
 
-module.exports = sum;
+module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,39 @@ 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.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 one number, returns that number", () => {
+    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
-
+  test("sums array with negative numbers", () => {
+    expect(sum([-1, -2, 3, 4])).toBe(4);
+  });
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+  test("sums array with decimals", () => {
+    expect(sum([1.5, 2.5, 3])).toBe(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("ignores non-number values", () => {
+    expect(sum(["hello", 10, null, 20, undefined, 5])).toBe(35);
+  });
 
 // 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 for array with only non-number values", () => {
+  expect(sum(["hello", null, undefined, {}, [], "42"])).toBe(0);
+});

Sprint-1/refactor/includes.js

@@ -1,8 +1,5 @@
-// 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;
     }