# Let us start by creating a simple list of numbers.
numbers = [2, 7, 4, 10, 3, 5, 8, 1, 6]
print(numbers)

# To get the first item, use index 0.
first_number = numbers[0]
print(first_number)

# To get the fourth item, use index 3.
fourth_number = numbers[3]
print(fourth_number)

# Let us use input so you can select a position yourself!
index = int(input('Type an index from 0 to 8: '))
selected = numbers[index]
print('You picked:', selected)

# Get a slice from the second to fourth number.
slice_example = numbers[1:4]
print(slice_example)

# Create an empty list for even numbers.
evens = []
for n in numbers:
    if n % 2 == 0:
        evens.append(n)
print(evens)

# We can also use a list comprehension for filtering.
odds = [n for n in numbers if n % 2 != 0]
print(odds)

# Get a number from the user.
threshold = int(input('Show me all numbers greater than: '))
greater = [n for n in numbers if n > threshold]
print('These numbers are greater:', greater)

# Try to select a number, but check if the index is valid.
pos = int(input('Pick an index: '))
if 0 <= pos < len(numbers):
    print('Your choice:', numbers[pos])
else:
    print('Sorry, that index is out of range.')
    

# Another way: Use try-except to catch errors gracefully.
try:
    idx = int(input('Which index do you want? '))
    print('Here you go:', numbers[idx])
except IndexError:
    print('Oops! That spot is out of range.')
    

# Filter numbers that are even and greater than five.
specials = [n for n in numbers if n % 2 == 0 and n > 5]
print(specials)

# Filtering works with words too!
words = ['cat', 'dog', 'rabbit', 'deer', 'cow', 'crow']
long_words = [w for w in words if len(w) > 3]
print(long_words)

# Make a list of odd numbers and sort them.
my_odds = [n for n in numbers if n % 2 != 0]
my_odds.sort()
print(my_odds)

# You can also use sorted() if you do not want to change the original list.
sorted_evens = sorted([n for n in numbers if n % 2 == 0])
print(sorted_evens)
# numbers list stays unchanged.

# List of guest ages
ages = [5, 28, 18, 40, 16, 21, 10, 19]

# Adults are 18+
adults = [a for a in ages if a >= 18]
print('Adults:', adults)

# Try also getting the number of kids in one line.
kids = [a for a in ages if a < 18]
print('Kids:', kids)

# Try to filter for guests over one hundred years old.
over_100 = [a for a in ages if a > 100]
print(over_100)

# Function to check if an age is even.
def is_even_age(age):
    return age % 2 == 0

even_ages = [a for a in ages if is_even_age(a)]
print('Even ages:', even_ages)