Python Lists and Strings Practice

Why I studied this

I’m learning Python and I wanted to get better at using lists and strings.
These are basic but really important in many programs, so I tried different ways to use them.

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What I did

Making and checking a list

words = ["red", "green", "blue"]
print(words[0])
print(words[1])
print(words[2])

This is how I made a list and printed each item by using index numbers.

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Adding new items and checking the list

words.append("black")
words.append("cyan")
print(words)
print(len(words))
print(words.count("red"))
print(words.index("red"))

I used append() to add new items.
len() shows the number of items.
count() tells how many times something appears.
index() gives the position of the item.

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Checking if something is in the list

if "yellow" in words:
    print(words.index("yellow"))
else:
    print("yellow not found")

This checks if “yellow” is in the list.
If it is, it prints the index. If not, it says it’s not there.

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Reversing the list

print(words[::-1])

This line shows how to print the list in reverse order using slicing.

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Lists can change, strings can’t

words[0] = "white"

s = "white"
s = s.replace("w", "W")
s2 = "W" + s[1:]

You can change lists easily, but strings are different.
You have to make a new string to “change” something.

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Turning lists into strings and back

words.extend(["brown", "violet", "purple", "magenta"])
s = ", ".join(words)
words2 = s.split(", ")

This turns a list into a string and then back into a list using join() and split().

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Slicing a number list

numbers = [1,2,3,4,5,6,7,8,9,10]
print(numbers[0::2])  # Even positions
print(numbers[1::2])  # Odd positions

This prints every second number starting from index 0 or 1.

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Making empty lists and adding stuff

names = []
names.append("John")
names.append("Alex")
names.append("Sarah")

names2 = list()
names2.append("Rose")
names2.append("Lily")
names2.append("Daisy")

You can make empty lists using [] or list() and then add items with append().

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What I learned

I practiced how to use lists and strings in different ways.
Now I understand slicing, appending, joining, and changing things better.
I also learned that strings are not like lists because they can’t be changed directly.

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What I want to do next

Next time I want to try using sets and dictionaries.
I also want to try making small projects that use lists and strings together.