London | 26-ITP-Jan | Angela McLeary | Sprint 1 | Sprint 1

Sprint-1/fix/median.js

@@ -6,9 +6,50 @@
 // 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;
+  //If the items are not an array or if the array is empty return null
+  const isItANumber = list.map((value) => {
+    if (value === null || value === undefined) {
+      return NaN;
+    }
+    //checks for null and undefined and ignore them.
+
+    if (typeof value === "number") {
+      return value;
+    }
+    // check for actual numbers and keep them.
+
+    return NaN;
+  });
+  //everything else is NaN.
 
+  const numbers = isItANumber.filter((num) => Number.isFinite(num));
+  if (numbers.length === 0) return null;
+  //checks the array before sorting and removing anything that is not a valid items and excludes NaN, Infinity and -Infinity.
+  const sortedList = [...numbers].sort((a, b) => a - b);
+  //Sorts the numbers without modifying the original array. This is useful but not always necessary.
+  const middleIndex = Math.floor(sortedList.length / 2);
+  //finds the median position
+  if (sortedList.length % 2 === 0) {
+    // if the list length is even, average the two middle numbers
+    return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
+    //It finds the middles of the array and selects the number before the middle and and adds the next number then divides by 2 when number is even.
+  }
+  return sortedList[middleIndex];
+  //if it is odd it returns the middle number
+}
+//checking
+// console.log(calculateMedian([1, 2, "3", null, undefined, 4])); // 2
+// console.log(calculateMedian([1, 2, 3, 4])); // 2.5
+// console.log(calculateMedian([110, 20, 0])); //20
+// console.log(calculateMedian([1, "apple", 2, null, 5, undefined])); // 2
+// console.log(calculateMedian("not array")); // null
+// console.log(calculateMedian("")); // null
 module.exports = calculateMedian;
+
+//check list
+// Is the input valid? ie not a string?
+//Validate what is valid input should be
+// sort input and put in new array
+//calculate median
+//check output

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))
   );
 
   [
@@ -24,7 +25,8 @@ 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]", () => {
@@ -33,8 +35,17 @@ describe("calculateMedian", () => {
     expect(list).toEqual([3, 1, 2]);
   });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for non-numeric array (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +56,7 @@ 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 +1,22 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (arr.length === 0) {
+    //checks if array is empty
+    return arr;
+  };
+  const newArray = []; // to store the new values after checking and deduplicating
+  for (let i = 0; i < arr.length; i++) {
+    // checks every item in array for dupes
+    if (!newArray.includes(arr[i])) {
+      //checks if new item is already in newArray
+      newArray.push(arr[i]); // adds new item !in newArray and appends it
+    }
+  };
+  return newArray; // returns new array without duplicates/empty
+};
+
+// console.log(dedupe([])); // prints: []
+// console.log(dedupe([1, 2, 3])); // prints: [ 1, 2, 3 ]
+// console.log(dedupe([5, 1, 1, 2, 3, 2, 5, 8])); // prints: [ 5, 1, 2, 3, 8 ]
+// console.log(dedupe(["a", "a", "a", "b", "b", "c"])); // prints: [ 'a', 'b', 'c' ]
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,29 @@ E.g. dedupe([1, 2, 1]) returns [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 has no duplicates, it returns a copy of the original array", () => {
+ const originalArray = [1, 2, 3];
+ const result = dedupe(originalArray);
+  expect(result).toEqual(originalArray);
+  expect(result).not.toBe(originalArray);
+});
 
 // Given an array of 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 the duplicates preserving the first occurrence of each element", () => {
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+  expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+  expect(dedupe(["z", "y", "w", "w", "u", "u"])).toEqual(["z", "y", "w", "u"]);
+});
 // Then it should return a new array with duplicates removed while preserving the 
 // first occurrence of each element from the original array.
+// updated version

Sprint-1/implement/max.js

@@ -1,4 +1,12 @@
 function findMax(elements) {
-}
+  if (!Array.isArray(elements)) return null;
 
+  if (elements.length === 0) return -Infinity;
+  // must include declaration for infinity or test fails.
+  const numbers = elements.filter((num) => Number.isFinite(num));
+  if (numbers.length === 0) return NaN;
+  // it returns NaN if no numbers found, there is  no need to sort the numbers
+  return Math.max(...numbers);
+}
+//console.log(findMax([200, 5, 8, 15, 90, 12]));
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,51 @@ 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, it 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, it returns that number", () => {
+  expect(findMax([1])).toEqual(1);
+});
 
 // 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, it returns the largest overall number", () => {
+  expect(findMax([-5, 35, 15, -55])).toEqual(35);
+});
 
 // 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([-55, -35, -15, -5])).toEqual(-5);
+});
+
 // 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, it returns the largest decimal number", () => {
+  expect(findMax([5.5, 3.5, 1.5, 0.5])).toEqual(5.5);
+});
+
 // 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("ignores non-number values and returns the max number", () => {
+  expect(findMax(["Not", "A", "Number", "300", 75, 85, 105])).toEqual(105);
+});
+
 // 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 non-number values, returns Not a Number (NaN)", () => {
+  expect(findMax(["a", "b", "c"])).toBeNaN(); // note: NaN !== NaN,
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,15 @@
 function sum(elements) {
+  const numbers = elements.filter((num) => Number.isFinite(num));
+
+  if (numbers.length === 0 && elements.length > 0) return NaN;
+
+  return numbers.reduce((total, nextNumber) => total + nextNumber, 0);
 }
+// console.log(sum([])); // 0
+// console.log(sum([1])); // 1
+// console.log(sum([5, 2, -3])); //4
+// console.log(sum([1.5, 2.5, 3.5])); //7.5
+// console.log(sum(["h", 2.5, "e", 3.5])); //6
+// console.log(sum(["a", "b", "c", "d"])); //Nan
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,42 @@ 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, it returns 0", () => {
+  expect(sum([])).toEqual(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 just one number, it returns that number", () => {
+  expect(sum([1])).toEqual(1);
+});
 
 // 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 containing negative numbers, it returns the correct sum", () => {
+  expect(sum([5, 2, -3])).toEqual(4);
+});
 
 // 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, it should return the total sum", () => {
+  expect(sum([1.5, 2.5, 3.5])).toBeCloseTo(7.5);
+});
 // 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 containing non-number values, it should ignore the non-numbers and sum the numerical elements", () => {
+  expect(sum(["h", 2.5, "e", 3.5])).toEqual(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
+test("given an array with non-number values, returns Not a Number (NaN)", () => {
+  expect(sum(["a", "b", "c"])).toBeNaN(); // note: NaN !== NaN,
+});
+
+//