Smart Ways to Utilize Lists

Since lists are a type of data structure, you can apply various operations to process data efficiently.

For instance, applying the + operation to two lists will merge them into one, and applying the x operation to a list will repeat the list by that number of times.

In this lesson, we will explore commonly used operations and methods (functions that perform specific tasks) on lists.

Adding two lists will concatenate them into a single list.

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# List Addition
list1 = [1, 2, 3]
list2 = [4, 5, 6]

# Combine two lists into the variable 'combined'
combined = list1 + list2

# Output: [1, 2, 3, 4, 5, 6]
print(combined)

When you multiply a list by an integer, it creates a new list with the original list repeated that many times.

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# List Multiplication
numbers = [0, 1, 2]

# Repeat the list 2 times and store in 'multiplied'
multiplied = numbers * 2

# Output: [0, 1, 2, 0, 1, 2]
print(multiplied)

To find out how many elements are in a list, use the len() function.

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fruits = ["apple", "banana", "cherry"]

# Store the length of the list in the variable 'length'
length = len(fruits)

print(length)  # Output: 3

To find the smallest or largest values in a list, use the min() and max() functions.

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# Finding the Minimum Value
numbers = [5, 2, 9, 1, 7]

# Store the minimum value in the variable 'min_value'
min_value = min(numbers)

print(min_value)  # Output: 1


# Store the maximum value in the variable 'max_value'
max_value = max(numbers)

print(max_value)  # Output: 9

To sum the elements of a list of numbers, use the sum() function.

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# Calculating the Sum of List Elements
expenses = [250, 150, 75, 300]

# Store the sum of the list in the variable 'total'
total = sum(expenses)

print(total)  # Output: 775

To verify if a list contains a certain value, use the in operator.

The in operator returns a boolean value of True or False.

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# Checking for the Presence of an Element in a List
fruits = ["apple", "banana", "cherry"]

print("apple" in fruits)  # Output: True
print("orange" in fruits)  # Output: False

To find the position of a specific value in a list, use the index() method.

This method returns the position (index) where the value first appears.

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# Finding the Index of a Specific Value in a List
fruits = ["apple", "banana", "cherry", "banana"]
index = fruits.index("banana")

print(index)  # Output: 1

The first occurrence of "banana" is the second element, but since indexing starts at 0, it prints 1.

To sort a list in ascending or descending order, use the sort() method.

Add the reverse=True option to sort the elements in descending order.

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# Sorting a List in Ascending Order
numbers = [5, 2, 9, 1, 7]
numbers.sort()
print(numbers)  # Output: [1, 2, 5, 7, 9]

# Sorting a List in Descending Order
numbers.sort(reverse=True)
print(numbers)  # Output: [9, 7, 5, 2, 1]

Note: The sort() method modifies the original list and does not return a new list. To maintain the original list, use the sorted() function.