Sheffield | 25-ITP-May | Declan Williams | Data-Groups-Sprint 1

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) {
+  // checks if "list" is an array if not return's null.
+  if(!Array.isArray(list)) return null;
+
+  // filter the non number values out of an array like "strings", "null's and undefined"
+  const numbers = list.filter( value => typeof value === `number` && !isNaN(value));
+
+  // if no numbers are left return null
+  if (numbers.length === 0) return null;
+
+  // sort numbers into ascending order
+  numbers.sort(function(a, b){
+    return a - b;
+  })
+
+  // finds the middle index based on filtered numbers length
   const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
-}
 
-module.exports = calculateMedian;
+  // return the correct median based on if its even or odd
+  if (numbers.length % 2 === 0){
+    // even length average of two middle numbers
+    return (numbers[middleIndex - 1] + numbers[middleIndex]) / 2;
+  } else {
+    // odd length returns the middle number
+    return numbers[middleIndex];
+  }
+}

Sprint-1/implement/dedupe.js

@@ -1 +1,17 @@
-function dedupe() {}
+function dedupe(array) {
+  // makes a new array to store non duplicate values
+  const newArray = [];
+
+  // loops over each item in the original array
+  for (const item of array) {
+    // checks if the values are not in the "newArray"
+    if (!newArray.includes(item)) {
+      // if item is not in "newArray" adds it to the array
+      newArray.push(item);
+    }
+  }
+  // returns the new deduped array
+  return newArray;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,22 @@ 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
+test("given an array with duplicates it removes any duplicates and preserves the first instance of each element", () => {
+  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 +1,33 @@
 function findMax(elements) {
-}
+    // makes an array to hold only numbers
+    const numbersOnly = []
+
+    // to loop through each element in the array
+    for (const item of elements){
+
+        // if the item is a number push it to the numbersOnly array
+        if (typeof item === `number`){
+            numbersOnly.push(item);
+        }
+    }
+    // start with the first number in the "numbersOnly" array
+    let max = numbersOnly[0];
+
+    // if the no numbers are found in the array returns -infinty
+    if (numbersOnly.length === 0) {
+        return -Infinity;
+    }
 
+    // loop for the largest number in the "numbersOnly" array
+    for (const num of numbersOnly) {
+        if (num > max) {
+            max = num;
+        }
+    }
+    return max;
+
+}
+console.log(findMax([30, 50, 10, 40])); // 50
+console.log(findMax(['hey', 10, 'hi', 60, 10])); // 60
+console.log(findMax([])); // -infinity
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,47 @@ 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 one 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", () => {
+    expect(findMax([-10, 5, -30, 27])).toBe(27);
+})
 
 // 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([-100, -10, -5, -50])).toBe(-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, returns the largest decimal", () => {
+    expect(findMax([1.5, 2.3, 0.7, ,3.14, 2.71])).toBe(3.14);
+});
 
 // 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 removes the 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([`hey`, `hi`, `hello`])).toBe(-Infinity);
+})

Sprint-1/implement/sum.js

@@ -1,4 +1,17 @@
 function sum(elements) {
+    if (elements.length === 0) return 0; // if array is input is empty returns 0
+
+   let total = 0; // create a variable to hold the sum
+
+   // iterate over each element in the array
+    for (const value of elements){
+        // checks if each of the values are numbers
+        if (typeof value === `number`){
+            // adds the numbers to the total sum
+            total += value;
+        }
+    }
+return total; // returns the total sum after the loop has finished adding all the numbers
 }
 
 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, 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 a single number return 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("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 in returns the correct total sum", () => {
+    expect(sum([10.5, 20.2, 30.3])).toBe(61.0);
+    expect(sum([10.5, -20.2, 30.3])).toBe(20.6);
+});
 
 // 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-numerical values ignore non-numerical and returns correct total sum", () => {
+    expect(sum([2, "hello", 26.5, "hey", -6.6, 8])).toBe(29.9);
+});
 
 // 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-numerical values returns 0", () => {
+    expect(sum(["a", "b", "c"])).toBe(0);
+});

Sprint-1/refactor/includes.js

@@ -1,12 +1,15 @@
 // 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];
+// iterate through each element in the list
+  for (const element of list){ 
+
+    // If an element matches the target, return true
     if (element === target) {
       return true;
     }
   }
+  // If no element matches the target, return false
   return false;
 }