Developing Algorithms
How to do simple operators in JS
Use the “+” operator to add two numbers in JavaScript
Use the “-“ operator to subtract two numbers in JavaScript
Use the “*” operator to multiply two numbers in JavaScript
Use the “/” operator to divide two numbers in JavaScript
Use the “%” operator to get the remainder of a division operation in JavaScript
Iterating
Iteration is going through a set of laws or objectives for the loops to complete. This allows for the desired objective to be completed.
Randomization
Raandomization is used to generate a random number. For example, RANDOM(a,b) would generate any number from a to b. Each result from randomization is equally likely to occur. Each execution might produce a different result.
Popcorn hack #1: How to find the mean in JS
%%js
// define an array
var arry = [4,62,3,38];
// define a function to calculate the mean using an inputted array
function calculateAverageOfArray(array) {
var total = 0;
var count = 0;
// add all the values of the array
jQuery.each(arry, function(index, value) {
total += value;
count++;
});
// take the sum of the array and divide it by the length of the array
return total / count;
}
console.log("The average of your list is " + calculateAverageOfArray(arry));
<IPython.core.display.Javascript object>
How to calculate the median
%%js
// define the function median that finds the median of an array numbers
function median(numbers) {
// sort the list numbers
const sorted = Array.from(numbers).sort((a, b) => a - b);
// find the index of the middle element in the array
const middle = Math.floor(sorted.length / 2);
// see if the array has an even length
if (sorted.length % 2 === 0) {
// if it's even then calculate the average of the middle two values
return (sorted[middle - 1] + sorted[middle]) / 2;
}
// if odd return the middle value
return sorted[middle];
}
// run median with the inputted array
console.log(median([1, 3, 8, 2, 6]));
<IPython.core.display.Javascript object>
How to calculate the mode in JS
%%js
// Create a function that finds the mode of an array
var mode = function mode(arr) {
// use the function "reduce" to go through every item in the list while collecting the data
return arr.reduce(function(current, item) {
// update the variable "val" with the frequency of "item" and increase it by 1.
var val = current.numMapping[item] = (current.numMapping[item] || 0) + 1;
// check if the mode of "item" is greater than the greatest mode so far
if (val > current.greatestFreq) {
// if it is then update the mode
current.mode = item;
current.greatestFreq = val;
}
// return the updated value of "current" then repeat the process
return current;
}, {mode: null, greatestFreq: -Infinity, numMapping: {}}).mode;
};
// run the mode function with an inputted array and print it to the console
console.log(mode([6, 6, 7, 7, 7, 8, 8, 8, 8, 8, 9, 10,7,7,7,7,7,7,7,7]));
<IPython.core.display.Javascript object>
One way to sort a list
numList = [43, 2, 6, 2, 96, 32]
numList.sort()
print(numList)
[2, 2, 6, 32, 43, 96]
Another way to sort a list
def bubbleSort(arr):
n = len(arr)
swapped = False # a boolean to keep track of whether a swap has occurred.
for i in range(n-1): # a loop to go iterate through the entire array
for j in range(0, n-i-1): # loop to compare adjacent elements
if arr[j] > arr[j + 1]:
# if current element is greater than the next element then swap them
swapped = True
arr[j], arr[j + 1] = arr[j + 1], arr[j]
if not swapped:
# if no swaps happen then the array is sorted
return
arr = [64, 34, 25, 12, 22, 11, 90]
bubbleSort(arr) # call the function to sort the array
print("Sorted array is:")
for i in range(len(arr)):
print("%d" % arr[i], end=" ")
Sorted array is:
11 12 22 25 34 64 90
What does this code do?
import random
randomNumber = random.randint(1, 100)
attempts = 0
def startGame():
print("Welcome to the Number Guessing Game!")
print("I'm thinking of a number between 1 and 100.")
print("Try to guess the number.")
askForGuess()
def askForGuess():
input_str = input("Enter your guess (between 1 and 100): ")
try:
guessedNumber = int(input_str)
checkGuess(guessedNumber)
except ValueError:
print("Please enter a valid number.")
askForGuess()
def checkGuess(guess):
global attempts
if guess < randomNumber:
print("Try a higher number.")
attempts += 1
askForGuess()
elif guess > randomNumber:
print("Try a lower number.")
attempts += 1
askForGuess()
else:
attempts += 1
print(f"Congratulations! You guessed the number {randomNumber} in {attempts} attempts.")
startGame()
Homework Hacks:
- Find the median test grade of a class
- Create a simple game using random numbers