3.8.1 For Loops

For Loops

• A for loop is used in python for iterating over a sequence of code.
• Through using a for loop, we can execute a set of commands that are in a list or set.
• Here is an example

vegetables = ["🥒", "🥑", "🥕"]
for x in vegetables:
  print(x)

🥒
🥑
🥕

Looping Through a String

• Even strings are iterable objects and contain a sequence of characters
• Here in an example

for x in "avocado":
  print(x) 

a
v
o
c
a
d
o

The Break Statement

• A break statement can aid us in stopping a loop before it has loops all the items.
• Here is an example

vegetables = ["🥒", "🥑", "🥕"]
for x in vegetables:
  print(x)
  if x == "🥑":
    break

🥒
🥑

For Loops in Javascript

• For Loops that are iterated over arrays can be in executed in Javascript in addition to Python.
• Here is an example

%%javascript
const fruits = ['apple', 'banana', 'cherry'];

for (let i = 0; i < fruits.length; i++) {
    console.log(fruits[i]);
}

<IPython.core.display.Javascript object>

Looping Through a String in Javascript

• This Loop is used to help iterate through every character in the string but in javascript
• Here is an example

%%javascript
const str = "Hello, World!";

for (let i = 0; i < str.length; i++) {
    console.log(str[i]);
}

<IPython.core.display.Javascript object>

Popcorn Hack #1

• This first hack is in Javascript and allows you to count from 0 to 4.
• Through using this simple hack you can utilize for loops and create an array of numbers

%%javascript
for (let i = 0; i < 5; i++) {
    console.log(i);
}

<IPython.core.display.Javascript object>

Popcorn Hack #2

• The second hack is the use of code to make an array of fruits using Python
• Through this hack you can use minimal code to list your favorite things

fruits = ['🍎', '🍌', '🍒']

for fruit in fruits:
    print(fruit)

🍎
🍌
🍒

Homework

• Try to add in two of the loops into your code, one in python and one in javascript.
• This will help build your understanding on loops in both javascript and python
• Additionally, try looping through a dictionary in order to be more creative with your code and personalize it

person = {'name': 'Arshia', 'age': 16}

# Looping through keys
for key in person:
    print(key, person[key])

# Looping through values
for value in person.values():
    print(value)

# Looping through keys and values
for key, value in person.items():
    print(key, value)

name Arshia
age 16
Arshia
16
name Arshia
age 16