London | 26-ITP-Sep | Shirin Panahian | Sprint 1 | Complete sprint 1 exercises

Sprint-1/fix/median.js

@@ -6,9 +6,30 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+
+  if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+
+  for (const item of list) {
+    if (!Number.isFinite(item)) {
+      throw new Error("calculateMedian requires an array of numbers");
+    }
+  }
+
+  const listLength = list.length;
+  const copy = [...list];
+  const middleIndex = Math.floor(listLength / 2);
+  copy.sort((a, b) => a - b);
+  if (listLength % 2 === 0) {
+    const median = (copy[middleIndex - 1] + copy[middleIndex]) / 2;
+    return median;
+  } else {
+    return copy[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,14 @@
-function dedupe() {}
+function dedupe(list) {
+  if (list.length === 0) {
+    return [];
+  }
+  const newList = [];
+  for (const item of list) {
+    if (newList.includes(item)) {
+      continue;
+    }
+    newList.push(item);
+  }
+  return newList;
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -4,7 +4,7 @@ Dedupe Array
 
 📖 Dedupe means **deduplicate**
 
-In this kata, you will need to deduplicate the elements of an array
+In this Kata, you will need to deduplicate the elements of an array
 
 E.g. dedupe(['a','a','a','b','b','c']) returns ['a','b','c']
 E.g. dedupe([5, 1, 1, 2, 3, 2, 5, 8]) returns [5, 1, 2, 3, 8]
@@ -16,13 +16,43 @@ 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");
+describe("dedupe", () => {
+  it("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
+  it("given an array, it returns an deduplicate array", () => {
+    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]);
+  });
 
-// Given an array of strings or numbers
-// When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
-// first occurrence of each element from 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
+  it("Given an array with no duplicates, it returns a copy of the original array", () => {
+    const originalArray = ["d", "s", "t", "c"];
+    const result = dedupe(originalArray);
+
+    expect(result).toEqual(originalArray);
+    expect(result).not.toBe(originalArray);
+
+    expect(dedupe([5, 4, 3, 2, 1])).toEqual([5, 4, 3, 2, 1]);
+    expect(dedupe([7, 8, 9])).toEqual([7, 8, 9]);
+  });
+
+  // Given an array of strings or numbers
+  // When passed to the dedupe function
+  // Then it should return a new array with duplicates removed while preserving the
+  // first occurrence of each element from the original array.
+  it("Given an array with duplicates, it removes duplicates while preserving the first occurrence", () => {
+    expect(dedupe(["d", "s", "s", "t", "c", "d", "s", "t", "c", "d"])).toEqual([
+      "d",
+      "s",
+      "t",
+      "c",
+    ]);
+    expect(dedupe([5, 4, 5, 4, 2, 1, 5, 3, 4])).toEqual([5, 4, 2, 1, 3]);
+    expect(dedupe([7, 2, 7, 8, 9])).toEqual([7, 2, 8, 9]);
+  });
+});

Sprint-1/implement/describe-median.js

@@ -20,6 +20,13 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) {
+  try {
+    const result = `The median is ${calculateMedian(list)}`;
+    return result;
+  } catch (error) {
+    return `Could not calculate a median: ${error.message}`;
+  }
+}
 
 module.exports = describeMedian;

Sprint-1/implement/describe-median.test.js

@@ -21,11 +21,34 @@ const describeMedian = require("./describe-median.js");
 // When passed to describeMedian
 // Then it should return "The median is " followed by the median
 // Delete this test.todo and replace it with a test.
-test.todo('given [1, 2, 3], returns "The median is 2"');
-
-// Given an empty array
-// When passed to describeMedian
-// Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
+describe("describeMedian", () => {
+  it("Given array of positive numbers, it returns the correct message", () => {
+    expect(describeMedian([1, 2, 6])).toEqual("The median is 2");
+  });
+
+  // Given an empty array
+  // When passed to describeMedian
+  // Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
+  it("returns an error message when given an empty array", () => {
+    expect(describeMedian([])).toEqual(
+      "Could not calculate a median: calculateMedian requires a non-empty array"
+    );
+  });
+  // Given something that isn't an array of numbers, e.g. "banana"
+  // When passed to describeMedian
+  // Then it should return "Could not calculate a median: calculateMedian requires an array of numbers"
+  it("returns an error message when given an empty array", () => {
+    expect(describeMedian("banana")).toEqual(
+      "Could not calculate a median: calculateMedian requires an array of numbers"
+    );
+    expect(describeMedian([3, "5", 8])).toEqual(
+      "Could not calculate a median: calculateMedian requires an array of numbers"
+    );
+    expect(describeMedian(42)).toEqual(
+      "Could not calculate a median: calculateMedian requires an array of numbers"
+    );
+  });
+});
 
 // Given something that isn't an array of numbers, e.g. "banana"
 // When passed to describeMedian

Sprint-1/implement/max.js

@@ -1,4 +1,24 @@
 function findMax(elements) {
-}
+  if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+  }
+  for (const value of elements) {
+    if (!Number.isFinite(value)) {
+      throw new Error("findMax requires an array of numbers");
+    }
+  }
+
+  const arrLength = elements.length;
+  let maxNum = -Infinity;
+  if (arrLength === 0) {
+    return [-Infinity];
+  }
 
+  for (const item of elements) {
+    if (maxNum < item) {
+      maxNum = item;
+    }
+  }
+  return maxNum;
+}
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,87 @@ 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");
+describe("findMax", () => {
+  it("given an empty array,returns -Infinity", () => {
+    expect(findMax([])).toEqual(-Infinity);
+  });
 
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
+  // Given an array with one number
+  // When passed to the max function
+  // Then it should return that number
+  it("given an array with one number,returns that number", () => {
+    expect(findMax([5])).toEqual(5);
+    expect(findMax([20])).toEqual(20);
+  });
 
-// Given an array with both positive and negative numbers
-// When passed to the max function
-// Then it should return the largest number overall
+  // Given an array with both positive and negative numbers
+  // When passed to the max function
+  // Then it should return the largest number overall
+  it("given an array with both positive and negative numbers, return the largest number overall", () => {
+    expect(findMax([5, 8, 3, 0, -1, 2, 16, -8, -16])).toEqual(16);
+    expect(findMax([-10, -5, -2, -20, 3, -1])).toEqual(3);
+    expect(findMax([-100, 50, -30, 25, 0, 75, -5])).toEqual(75);
+  });
 
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
+  // Given an array with just negative numbers
+  // When passed to the max function
+  // Then it should return the closest one to zero
+  it("given an array with just negative numbers, return the closest one to zero", () => {
+    expect(findMax([-5, -8, -3, -76, -2, -16, -4])).toEqual(-2);
+    expect(findMax([-1, -2, -9, -100])).toEqual(-1);
+  });
 
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+  it("given an array with decimal numbers, returns the largest decimal number", () => {
+    expect(findMax([1.5, 3.7, 2.4, 5.9, 4.2])).toEqual(5.9);
+    expect(findMax([0.1, 0.9, 0.5])).toEqual(0.9);
+    expect(findMax([-1.5, -3.2, -0.5])).toEqual(-0.5);
+  });
 
-// Given an array containing a value that isn't a number
-// When passed to the max function
-// Then it should throw Error("findMax requires an array of numbers")
+  // Given an array containing a value that isn't a number
+  // When passed to the max function
+  // Then it should throw Error("findMax requires an array of numbers")
+  it("throws when given an array containing a value that isn't a number", () => {
+    expect(() => findMax(["banana"])).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
 
-// Given something that isn't an array at all, such as "hey", 42 or no argument
-// When passed to the max function
-// Then it should throw Error("findMax requires an array of numbers")
+    expect(() => findMax([10, "hello", 20])).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax([10, null, 20])).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax([10, NaN, 20])).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+  });
+  // Given something that isn't an array at all, such as "hey", 42 or no argument
+  // When passed to the max function
+  // Then it should throw Error("findMax requires an array of numbers")
+  it("throws when given something that isn't an array", () => {
+    expect(() => findMax("hey")).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax(42)).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax()).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax(null)).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+
+    expect(() => findMax({})).toThrow(
+      new Error("findMax requires an array of numbers")
+    );
+  });
+});

Sprint-1/implement/mean.js

@@ -1,3 +1,27 @@
-function calculateMean(list) {}
+function calculateMean(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+
+  if (list.length === 0) {
+    throw new Error("calculateMean requires a non-empty array");
+  }
+
+  for (const element of list) {
+    if (!Number.isFinite(element)) {
+      throw new Error("calculateMean requires an array of numbers");
+    }
+  }
+
+  let sum = 0;
+
+  list.forEach((item) => {
+    sum += item;
+  });
+
+  const mean = sum / list.length;
+
+  return mean;
+}
 
 module.exports = calculateMean;