🔢 NumPy — Arrays aur Math

pip install numpy

import numpy as np   # np alias standard hai
print(np.__version__)  # version check

import numpy as np

# 1D Array
arr1 = np.array([1, 2, 3, 4, 5])
print(arr1)         # [1 2 3 4 5]
print(arr1.shape)   # (5,)
print(arr1.dtype)   # int64

# 2D Array (Matrix)
arr2 = np.array([[1,2,3],[4,5,6]])
print(arr2.shape)   # (2, 3) — 2 rows, 3 cols

# Special arrays
zeros = np.zeros((3,3))   # 3x3 zeros
ones  = np.ones((2,4))    # 2x4 ones
eye   = np.eye(3)          # 3x3 identity
rng   = np.arange(0,10,2) # [0 2 4 6 8]
print(rng)

a = np.array([1,2,3,4])
b = np.array([10,20,30,40])

# Element-wise operations
print(a + b)   # [11 22 33 44]
print(a * b)   # [10 40 90 160]
print(a ** 2) # [1 4 9 16]
print(a * 2)  # [2 4 6 8] — broadcasting

# Statistics
print(np.sum(a))    # 10
print(np.mean(a))   # 2.5
print(np.max(a))    # 4
print(np.min(a))    # 1
print(np.std(a))    # Standard deviation

arr = np.array([[1,2,3],[4,5,6],[7,8,9]])

print(arr[0,0])    # 1 — row 0, col 0
print(arr[1,2])    # 6 — row 1, col 2
print(arr[0,:])    # [1 2 3] — row 0
print(arr[:,1])    # [2 5 8] — col 1
print(arr[0:2, 1:3]) # submatrix

# Chapter 21: NumPy — Advanced Practice
print("=== NumPy Practice ===")

# Example 1: Basic usage
result = "Python mein NumPy bahut powerful hai!"
print(result)

# Example 2: Real world use
data = ["NumPy", "Python", "Hindi", "PythonHindi.in"]
for item in data:
    print(f"Item: {item}")

print("\nPractice complete! Great job! 🎉")

# Chapter 21: NumPy  Arrays aur Math — Advanced Examples
# Yeh code copy karo aur run karo!

# Example 1: Basic concept
print("=== Chapter 21: NumPy  Arrays aur Math ===")

# Example 2: List operations
items = ["Python", "Hindi", "Code", "Practice"]
for i, item in enumerate(items, 1):
    print(f"{i}. {item}")

# Example 3: Dictionary usage
chapter_info = {
    "number": 21,
    "title":  "NumPy  Arrays aur Math",
    "level":  "Advanced",
    "done":   False
}
for key, value in chapter_info.items():
    print(f"  {key:10}: {value}")

# Example 4: Function
def practice_summary(chapter, completed=False):
    status = "Complete ✅" if completed else "In Progress ⏳"
    return f"Chapter {chapter}: {status}"

print(practice_summary(21))
print(practice_summary(21, True))