Practical2: Shopping Cart and calculation of averages

Mean, Median, and Mode

First we need some arrays of numbers on which to test our code.

var numbers1 = [1,2,3,4,5,6,7,8,9];
var numbers2 = [1,2,3,2,3,2,5,6,6,4,3,1,5,4,3];
var numbers3 = [1,2,3,1,2,3];
var mynumbers = [3,78,5,23,1,9,7,5];

function mean(numberlist){
    let sum = 0;
    for (i=0 ; i<numberlist.length; i++)
      sum += numberlist[i];
 
    return sum/numberlist.length;
}
                                

var numbers1 = [1,2,3,4,5,6,7,8,9];
var numbers2 = [1,2,3,2,3,2,5,6,6,4,3,1,5,4,3];
var numbers3 = [1,2,3,1,2,3];
var mynumbers = [3,78,5,23,1,9,7,5];
                                

The mean of numbers1 is 5.000
The mean of numbers2 is 3.333
The mean of numbers3 is 2.000
The mean of mynumbers is 16.375              
                                

function median(numberlist){
    var sortedList = numberlist.sort((a,b) => a-b);
    var index = numberlist.length / 2;
    if (Number.isInteger(index))
      return (sortedList[index] + sortedList[index-1])/2;
    else
      return sortedList[Math.floor(index)];
}
                                

var numbers1 = [1,2,3,4,5,6,7,8,9];
var numbers2 = [1,2,3,2,3,2,5,6,6,4,3,1,5,4,3];
var numbers3 = [1,2,3,1,2,3];
var mynumbers = [3,78,5,23,1,9,7,5];
                                

The mean of numbers1 is 5.000
The mean of numbers2 is 3.000
The mean of numbers3 is 2.000
The mean of mynumbers is 6.000              
                                

// Mode solution produced after class
// As result can be bimodal or multi-modal,
// the returned result is provided as an array
// mode of [3, 5, 4, 4, 1, 1, 2, 3] = [1, 3, 4].
function mode(numberlist) {
    let modes = [];
    let count = [];
    let number = 0;
    let maxIndex = 0;
    for (let i = 0; i < numberlist.length; i++) {
        number = numberlist[i];
        count[number] = (count[number] || 0) + 1;
        if (count[number] > maxIndex) {
            maxIndex = count[number];
        }
    }
    // For - in statement.
    // Push the number(s) with the highest appearance frequency
    // into modes array.
    for (let i in count) {
        if (count[i] === maxIndex) {
           modes.push(Number(i));
        }
    }
    return modes;
}
                                

var numbers1 = [1,2,3,4,5,6,7,8,9];
var numbers2 = [1,2,3,2,3,2,5,6,6,4,3,1,5,4,3];
var numbers3 = [1,2,3,1,2,3];
var mynumbers = [3,78,5,23,1,9,7,5];
                                

The mode of numbers1 is 1,2,3,4,5,6,7,8,9
The mode of numbers2 is 3
The mode of numbers3 is 1,2,3
The mode of mynumbers is 5              
                                

Shopping cart

To calcuate total prices and possible discounts, we first need to create some (fictional) shopping carts:

var cart1 = [
  {name: 'apples', price: 1.20, quantity: 1, type: "food"},
  {name: 'oranges', price: 1.05, quantity: 2, type: "food"},
  {name: 'pens', price: 0.5, quantity: 3, type: "stationary"},
  {name: 'A5 notebook', price: 1.50, quantity: 2, type: "stationary"}
]

var cart2 = [
  {name: 'pears', price: 1.00, quantity: 2, type: "food"},
  {name: 'salmon', price: 2.65, quantity: 1, type: "food"},
  {name: 'thumb drive', price: 21.95, quantity: 1, type: "computing"},
  {name: 'bucket', price: 1.50, quantity: 2, type: "home"},
  {name: 'easter egg', price: 2.45, quantity: 3, type: "food"}
]

let shoppingCart = [
    {
        name:"loaf of bread",
        type:"food",
        quantity:1,
        price:.85
    },
    {
        name:"multipack beans",
        type:"food",
        quantity:2,
        price:1
    },
    {
        name:"mushrooms",
        type:"food",
        quantity:10,
        price:.1
    },
    {
        name:"can of beer",
        type:"alcohol",
        quantity:4,
        price:1.1
    },
    {
        name:"prosecco",
        type:"alcohol",
        quantity:1,
        price:8.99
    },
    {
        name:"steak",
        type:"food",
        quantity:2,
        price:3.99
    },
    {
        name:"blue cheese",
        type:"food",
        quantity:1,
        price:2.99
    },
    {
        name:"candles",
        type:"home",
        quantity:3,
        price:1.99
    },
    {
        name:"cheesecake",
        type:"food",
        quantity:1,
        price:4.99
    },
    {
        name:"onions",
        type:"food",
        quantity:3,
        price:.4
    },
];

Functions

Simple function to calculate the total cost of a shopping cart

function cartPrice(cart) {
  let totalPrice = 0;
  for (i=0 ; i<cart.length ; i++)
  {
    currentItem = cart[i];
    totalPrice += currentItem.price * currentItem.quantity;
  }
  return totalPrice;
}

Pendantic function to calculate the total cost of a shopping cost. Also applies a 30% discount to food items

function shoppingTotal(cart) {
  let totalPrice = 0;
  for (let i=0 ; i<cart.length ; i++) {
    let itemPrice = cart[i].price;
    if (cart[i].type === 'food') {
      itemPrice = .8 * itemPrice;
    }
    let itemQuantity = cart[i].quantity;
    let itemTotalPrice = itemPrice * itemQuantity;
    totalPrice = totalPrice + itemTotalPrice;
  }
  return totalPrice.toFixed(2);
}

More sophisticated function that takes a discount amount and the type of product to apply the discount to as arguments.

function shoppingTotalBetter(cart, discountAmount, type) {
  let totalPrice = 0;
  for (let i=0 ; i<cart.length ; i++) {
    let itemPrice = cart[i].price;
    if (cart[i].type === type) {
      itemPrice = (100 - discountAmount)/ 100 * itemPrice;
    }
    let itemQuantity = cart[i].quantity;
    let itemTotalPrice = itemPrice * itemQuantity;
    totalPrice = totalPrice + itemTotalPrice;
  }
  return totalPrice.toFixed(2);
}

Finally a function to filter the cart based on price (with a random name). The variable quantity specifies whether the quantity of the item in the shopping basket should be taken into account in this calculation.

function ted(cart,lowPrice, highPrice, quantity){
  let arrItems = [];
  for (let i=0 ; i<cart.length; i++){
    if (quantity === true) {
      itemPrice = cart[i].price * cart[i].quantity;
    }
    else {
      itemPrice = cart[i].price;
    }

    if (itemPrice >= lowPrice && itemPrice <= highPrice){
      arrItems.push(cart[i]);
    }
  }
  return arrItems;
}

console.log('cart1 costs £'+cartPrice(cart1).toFixed(2));
console.log('cart2 costs £'+cartPrice(cart2).toFixed(2));
console.log('the combined cart costs £'+cartPrice(cart1.concat(cart2)).toFixed(2));
console.log('shoppingCart costs £'+cartPrice(shoppingCart).toFixed(2));
console.log('shoppingCart costs £'+shoppingTotal(shoppingCart));
console.log('shoppingCart with 20% discount on food costs £'+shoppingTotalBetter(shoppingCart, 20,'food'));
console.log('shoppingCart with 20% discount on home costs £'+shoppingTotalBetter(shoppingCart, 20,'home'));
console.log('shoppingCart with 1% discount on alcohol costs £'+shoppingTotalBetter(shoppingCart, 1,'alcohol'));
console.log('shoppingCart with 10% discount on home costs £'+shoppingTotalBetter(shoppingCart, 10,'food'));
console.log(ted(shoppingCart,2,5,true));
console.log(ted(shoppingCart,2,5,false));
                

cart1 costs £7.80
cart2 costs £36.95
the combined cart costs £44.75
shoppingCart costs £40.37
shoppingCart costs £36.17
shoppingCart with 20% discount on food costs £36.17
shoppingCart with 20% discount on home costs £39.18
shoppingCart with 1% discount on alcohol costs £40.24
shoppingCart with 10% discount on home costs £38.27