Sheffield | 25-ITP-Sep | Jak Rhodes-Smith | Sprint 1 | Data Groups

Sprint-1/fix/median.js

@@ -6,9 +6,27 @@
 // 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;
+  if (!Array.isArray(list) || list.length === 0) {
+    return null;
+  }
+
+  const numbers = list
+    .filter((val) => typeof val === "number")
+    .sort((a, b) => a - b);
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  const middleIndex = Math.floor(numbers.length / 2);
+
+  if (numbers.length % 2 === 0) {
+    const lowerMiddle = numbers[middleIndex - 1];
+    const upperMiddle = numbers[middleIndex];
+    return (lowerMiddle + upperMiddle) / 2;
+  } else {
+    return numbers[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,8 @@
-function dedupe() {}
+function dedupe(elements) {
+  return elements.reduce(
+    (unique, ele) => (unique.includes(ele) ? unique : [...unique, ele]),
+    []
+  );
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,23 @@ 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("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
+// Then it should remove the duplicate values, preserving the first occurrence of each element
+test("given an array with duplicates, it removes duplicates preserving first occurrence", () => {
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).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) {
+  if (elements.length === 0) {
+    return -Infinity;
+  }
+
+  const numbers = elements
+    .filter((val) => typeof val === "number")
+    .sort((a, b) => a - b);
+
+  return Math.max(...numbers);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -15,29 +15,51 @@ 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 empty array
+// When passed to the max function
+// Then it should return -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 number", () => {
+  expect(findMax([-10, 0, 5, 3, 2])).toBe(5);
+});
 
 // 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 to zero", () => {
+  expect(findMax([-5, -10, -3])).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])).toBe(2.3);
+});
 
 // 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(["hey", 10, "hi", 60, 10])).toBe(60);
+});
 
 // 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", "b", "c"])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,10 @@
 function sum(elements) {
+  return (
+    elements
+      .filter((val) => typeof val === "number")
+      // Returns initial value(0) for empty arrays
+      .reduce((total, current) => total + current, 0)
+  );
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,41 @@ 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("given an array with one number, returns that number", () => {
+  expect(sum([5])).toBe(5);
+});
 
 // 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([10, -5, 20, -3])).toBe(22);
+});
 
 // 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 correct sum", () => {
+  expect(sum([10.5, 20.3, 5.2])).toBe(36);
+});
 
 // 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 sums numbers", () => {
+  expect(sum(["hey", 10, "hi", 60, 10])).toBe(80);
+});
 
 // 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(["hey", "hi", "hello"])).toBe(0);
+});

Sprint-1/refactor/includes.js

@@ -1,9 +1,8 @@
 // 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) {
+  for (let item of list) {
+    if (item === target) {
       return true;
     }
   }