Python Arrays

Python Arrays Tutorial

An array is a collection of elements stored in a single variable. In Python, arrays can be implemented using the array module or lists.

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1. Difference Between Lists and Arrays in Python

✅ For simple cases, Python lists work as dynamic arrays.
✅ For numerical operations, use array or NumPy for efficiency.

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2. Creating an Array in Python

To use an array, import the array module.

import array

# Creating an integer array
arr = array.array('i', [1, 2, 3, 4, 5])

print(arr)  # Output: array('i', [1, 2, 3, 4, 5])

✅ 'i' represents an integer array (other types: 'f' for float, 'd' for double, etc.).

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3. Accessing Array Elements

print(arr[0])  # Output: 1
print(arr[2])  # Output: 3

✅ Array indexing starts from 0 (like lists).

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4. Adding and Removing Elements

Append (Add at the end)

arr.append(6)
print(arr)  # Output: array('i', [1, 2, 3, 4, 5, 6])

Insert (Add at a specific index)

arr.insert(2, 10)  # Insert 10 at index 2
print(arr)  # Output: array('i', [1, 2, 10, 3, 4, 5, 6])

Remove an element

arr.remove(3)  # Removes first occurrence of 3
print(arr)  # Output: array('i', [1, 2, 10, 4, 5, 6])

Pop (Remove by index)

arr.pop(1)  # Removes element at index 1
print(arr)  # Output: array('i', [1, 10, 4, 5, 6])

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5. Looping Through an Array

Using a for loop

for num in arr:
    print(num, end=" ")  # Output: 1 10 4 5 6

Using a while loop

i = 0
while i < len(arr):
    print(arr[i], end=" ")
    i += 1
# Output: 1 10 4 5 6

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6. Finding the Length of an Array

print(len(arr))  # Output: 5

✅ len() returns the number of elements in the array.

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7. Slicing an Array

print(arr[1:4])  # Output: array('i', [10, 4, 5])
print(arr[:3])   # Output: array('i', [1, 10, 4])
print(arr[2:])   # Output: array('i', [4, 5, 6])

✅ Slicing works just like lists.

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8. Searching for an Element

print(arr.index(10))  # Output: 1 (Index of element 10)

✅ Returns the first index where the element is found.

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9. Sorting an Array

arr = array.array('i', [5, 2, 8, 1, 3])
arr = array.array('i', sorted(arr))

print(arr)  # Output: array('i', [1, 2, 3, 5, 8])

✅ The sorted() function returns a sorted array.

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10. Using NumPy for Advanced Arrays

Python’s built-in array module is limited. For more functionality, use NumPy.

Installing NumPy

pip install numpy

Creating a NumPy Array

import numpy as np

arr = np.array([1, 2, 3, 4, 5])
print(arr)  # Output: [1 2 3 4 5]

✅ NumPy is optimized for numerical operations and large datasets.

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Conclusion

• Use array for memory-efficient storage of same-type elements.
• Use lists for flexibility (mixing different types).
• Use NumPy for powerful numerical operations.

🚀 Let me know if you need more details on a specific part!

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