London | ITP-May-2025 | Seddiq Azam | Module-Data-Groups | Sprint 1

Sprint-1/fix/median.js

@@ -6,9 +6,28 @@
 // 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;
+  // Check if input is a valid array
+  if (!Array.isArray(list)) return null;
+
+  // Filter out non-numeric values
+  const numbers = list.filter(
+    (item) => typeof item === "number" && !isNaN(item)
+  );
+
+  // If no valid numbers, return null
+  if (numbers.length === 0) return null;
+
+  // Sort the numbers and calculate the median
+  const sorted = [...numbers].sort((a, b) => a - b);
+  const mid = Math.floor(sorted.length / 2);
+
+  // If the length of the sorted array is even, return the average of the two middle numbers
+  // If odd, return the middle number
+  if (sorted.length % 2 === 0) {
+    return (sorted[mid - 1] + sorted[mid]) / 2;
+  } else {
+    return sorted[mid];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,14 @@
-function dedupe() {}
+function dedupe(arr) {
+  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 +16,27 @@ 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", () => {
+  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
+  // 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
+  test("given an array with no duplicates, it returns a copy of the original array", () => {
+    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
+
+  test("given an array with strings or numbers, it removes duplicates", () => {
+    expect(dedupe(["a", "a", "b", "c", "b"])).toEqual(["a", "b", "c"]);
+    expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+    expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+  });
+});

Sprint-1/implement/max.js

@@ -1,4 +1,13 @@
 function findMax(elements) {
+  const numericValues = elements.filter(
+    (element) => typeof element === "number"
+  );
+  if (numericValues.length === 0) {
+    return -Infinity; // Return -Infinity if no numeric values are found
+  }
+  return Math.max(...numericValues);
 }
+// This function filters the input array to include only numeric values and then uses Math.max to find
+// the maximum value among them. If there are no numeric values, it returns -Infinity as
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,54 @@ 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([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 both positive and negative numbers, returns the largest number", () => {
+  expect(findMax([-10, 20, -30, 40, 5])).toBe(40);
+});
+
 // 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 just negative numbers, returns the closest one to zero", () => {
+  expect(findMax([-5, -10, -3, -8])).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 number", () => {
+  expect(findMax([1.5, 2.3, 0.7, 3.1])).toBe(3.1);
+});
+
 // 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 and ignores non-numeric values", () => {
+  expect(findMax(["hello", 10, "world", 50, 20])).toBe(50);
+});
+
 // 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(["apple", "banana", "cherry"])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,7 @@
 function sum(elements) {
+  return elements
+    .filter((element) => typeof element === "number") // Filter out non-numerical elements
+    .reduce((accumulator, currentValue) => accumulator + currentValue, 0); // Sum the numerical elements
 }
 
 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")
 
-// Given an array with just one number
-// When passed to the sum function
-// Then it should return that number
+describe("sum function", () => {
+  test("given an empty array, returns 0", () => {
+    expect(sum([])).toBe(0);
+    expect(sum([null, undefined])).toBe(0);
+  });
 
-// Given an array containing negative numbers
-// When passed to the sum function
-// Then it should still return the correct total sum
+  // Given an array with just one number
+  // When passed to the sum function
+  // Then it should return that number
 
-// 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 one number, returns that number", () => {
+    expect(sum([42])).toBe(42);
+    expect(sum([-10])).toBe(-10);
+  });
 
-// 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
+  // Given an array containing negative numbers
+  // When passed to the sum function
+  // Then it should still return the correct total sum
 
-// 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("given an array with negative numbers, returns the correct total sum", () => {
+    expect(sum([-10, -20, -30])).toBe(-60);
+    expect(sum([-10, 20, -30])).toBe(-20);
+  });
+
+  // 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 numbers, returns the correct total sum", () => {
+    expect(sum([1.5, 2.5, 3.0])).toBe(7.0);
+    expect(sum([1.1, 2.2, -3.3])).toBeCloseTo(0.0);
+  });
+
+  // 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, ignores them and returns the sum of numerical elements", () => {
+    expect(sum([10, "hello", 20, null, 30])).toBe(60);
+    expect(sum(["text", undefined, 5, 15])).toBe(20);
+  });
+
+  // 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("given an array with only non-number values, returns 0", () => {
+    expect(sum(["hello", null, undefined])).toBe(0);
+    expect(sum([])).toBe(0);
+  });
+});

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;
     }

Sprint-1/refactor/includes.test.js

@@ -1,7 +1,6 @@
 // Refactored version of includes should still pass the tests below:
 
 const includes = require("./includes.js");
-
 test("returns true when target is in array", () => {
   const currentOutput = includes(["a", "b", "c", "d"], "c");
   const targetOutput = true;
@@ -24,7 +23,7 @@ test("returns true when the target is in array multiple times", () => {
 });
 
 test("returns false for empty array", () => {
-  const currentOutput = includes([]);
+  const currentOutput = includes([], "anything");
   const targetOutput = false;
 
   expect(currentOutput).toEqual(targetOutput);

Sprint-1/stretch/aoc-2018-day1/solution.js

@@ -0,0 +1,5 @@
+function calculateFrequency(changes) {
+  return changes.reduce((acc, change) => acc + change, 0);
+}
+const input = [+1, -2, +3, +1];
+console.log(calculateFrequency(input)); // Output: 3