Introduction to One-Dimensional Arrays

What is an Array?

An array is a data structure that allows you to store multiple values of the same data type in a single variable.

Each value in an array is called an element, and each element is accessed by its index - a numeric value that represents its position in the array.

One-Dimensional Arrays

A one-dimensional array is the simplest form of an array, also known as a vector.

It consists of a single row or a single column of elements.

In other words, it is a linear arrangement of elements that can be accessed and manipulated using their indices.

["cat","dog","mouse","bear"]

Declaring and Initializing One-Dimensional Arrays

The syntax for declaring and initializing a one-dimensional array in Python is as follows:

array_name = [value1, value2, ..., value_n]

The values can be of any data type, and the list size is determined by the number of values provided.

Accessing Array Elements

Each element in a Python list (analogous to an array) can be accessed by its index.

The index starts from 0 for the first element and increments by 1 for each subsequent element.

For example, to access the second element of a list named my_list, you would use my_list[1].

Example

my_list = [10, 20, 30, 40, 50]  # Creating a list of integers

print(my_list[2]) # Output: 30 (third element)

Looping through arrays

To loop through a Python list (also known as traversing a list/array), you can use various types of loops, such as the for loop or the while loop. Here's how to do it using the for loop:

# Using a for loop to iterate through a list (array)
my_list = [10, 20, 30, 40, 50]
# Method 1: Using range and len
for i in range(len(my_list)):
    print(my_list[i])
# Method 2: Using direct iteration
for item in my_list:
    print(item)

In the first method, the range(len(my_list)) generates a sequence of indices from 0 to len(my_list) - 1, which are then used to access each element of the list using indexing.

In the second method, the for item in my_list: loop directly iterates through each element in the list.

Both methods achieve the same result: printing each element of the list. Choose the method that best fits your specific use case.

Searching Arrays

You can search for the index of an item in a list:

# Searching for an element in a Python list and printing its index
# Sample list
my_list = [10, 20, 30, 40, 50]
# Search value
search_value = 30
# Using the index() method
if search_value in my_list:
    index = my_list.index(search_value)
    print(f"{search_value} found at index {index}.")
else:
    print(f"{search_value} not found in the list.")

Adding Items to a List

You can add and remove items from a Python list using various built-in methods. Here's how you can do it:

Append:

Adds an item to the end of the list.

my_list = [10, 20, 30]
my_list.append(40)
print(my_list)  # Output: [10, 20, 30, 40]

Insert:

Inserts an item at a specific index.

my_list = [10, 20, 30]
my_list.insert(1, 15)
print(my_list)  # Output: [10, 15, 20, 30]

Extend:

Appends elements from another iterable to the end of the list.

my_list = [10, 20, 30]
my_list.extend([40, 50])
print(my_list)  # Output: [10, 20, 30, 40, 50]

Removing Items from a List

Remove: Removes the first occurrence of a specific value.

my_list = [10, 20, 30, 20, 40]

my_list.remove(20)

print(my_list) # Output: [10, 30, 20, 40]

Pop: Removes and returns the item at a specific index.

my_list = [10, 20, 30, 40]

removed_item = my_list.pop(1)

print(removed_item) # Output: 20

print(my_list) # Output: [10, 30, 40]