STEMTrainingGrounds

Lesson 5

Lesson 5 of 16

Lists

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Code Example

# List of integers
nums1 = [1, 2, 3]
print(nums1)

nums2 = [5, 10, 15]
print(nums2)


# List of decimals
prices = [1.5, 2.0, 3.25]
print(prices)

heights = [4.2, 5.1, 6.0]
print(heights)


# List of words
pets = ["Cat", "Dog", "Bird"]
print(pets)

colors = ["Red", "Blue", "Green"]
print(colors)

Instructions

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A list is like a backpack where you can store a whole collection of items together.
To make a list, we put all our items inside square brackets [ ].
We use commas to separate the items so Python knows where one ends and the next begins.
Your list can hold anything! It can be a group of numbers, decimals, or words.
When you give your list a name, like pets or colors, you can use it later in your code.
Just use print() with the list's name to see everything you stored inside it on the screen.

Code Example

# Case 1: List of short sentences (Example A)
quotes = ["Be kind", "Work hard", "Stay happy"]
print(quotes)

# Case 1: List of short sentences (Example B)
facts = ["The sky is blue", "Grass is green"]
print(facts)

# Case 2: List Indexing - Picking the first sentence
my_pets = ["I have a cat", "I have a dog", "I have a bird"]
print(my_pets[0])

# Case 2: List Indexing - Picking the last sentence
my_goals = ["Learn to code", "Play soccer", "Read a book"]
print(my_goals[2])

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When you have a list of sentences, Python gives each one a "hidden number" to help you find it.
The first sentence in your list is always number 0, the second is number 1, and the third is number 2.
To grab just one sentence, put its number inside square brackets [ ] right after the list name.

Code Example

# List of different data types
mix1 = [5, "Hello", 2.5]
print(mix1)

mix2 = ["Cat", 10, True]
print(mix2)


# List indexing (getting one item from the list)
items1 = [7, "Apple", 3.5]
print(items1[0])

items2 = ["Dog", 4, False]
print(items2[1])

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A list can hold different kinds of things, like numbers and words.
We use square brackets [ ] to get one item from a list.
Counting starts at 0, so [0] means the first item.
print() shows the list or the item on the screen.

Code Example

# Zip names with ages
names = ["Sam", "Alex"]
ages = [10, 12]

for name, age in zip(names, ages):
    print(name, age)


# Zip colors with objects
colors = ["Red", "Blue"]
things = ["Car", "Ball"]

for color, thing in zip(colors, things):
    print(color, thing)

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The zip() helper is like a zipper on a jacket that pulls two different lists together into pairs.
It takes the first item from the first list and matches it perfectly with the first item from the second list.
In your loop, you use two names like name, age to hold the two pieces of information at the same time.
This is the best way to keep related data together, like matching a person's name with their favorite color or their age.

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Lists

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Lesson 5 of 16

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# List of integers nums1 = [1, 2, 3] print(nums1) nums2 = [5, 10, 15] print(nums2) # List of decimals prices = [1.5, 2.0, 3.25] print(prices) heights = [4.2, 5.1, 6.0] print(heights) # List of words pets = ["Cat", "Dog", "Bird"] print(pets) colors = ["Red", "Blue", "Green"] print(colors)

# Case 1: List of short sentences (Example A) quotes = ["Be kind", "Work hard", "Stay happy"] print(quotes) # Case 1: List of short sentences (Example B) facts = ["The sky is blue", "Grass is green"] print(facts) # Case 2: List Indexing - Picking the first sentence my_pets = ["I have a cat", "I have a dog", "I have a bird"] print(my_pets[0]) # Case 2: List Indexing - Picking the last sentence my_goals = ["Learn to code", "Play soccer", "Read a book"] print(my_goals[2])

# List of different data types mix1 = [5, "Hello", 2.5] print(mix1) mix2 = ["Cat", 10, True] print(mix2) # List indexing (getting one item from the list) items1 = [7, "Apple", 3.5] print(items1[0]) items2 = ["Dog", 4, False] print(items2[1])

# Zip names with ages names = ["Sam", "Alex"] ages = [10, 12] for name, age in zip(names, ages): print(name, age) # Zip colors with objects colors = ["Red", "Blue"] things = ["Car", "Ball"] for color, thing in zip(colors, things): print(color, thing)