**Numpy (Numerical Python, `numpy`)** is a powerful library in Python that provides support for large, multi-dimensional arrays and matrices, along with a collection of high-level mathematical functions to operate on these arrays efficiently. 

It is a **fundamental package for scientific computing** with Python and is widely used in various fields, including data science, machine learning, numerical simulations, and more.

## Why do we need Numpy?
Key reasons why we need Numpy:

- **Efficient Array Operations**: provides efficient implementations of array operations;

- **Multi-dimensional Arrays**: enables manipulation of multi-dimensional arrays, facilitating handling of vectors, matrices, and higher-dimensional data;
- **Mathematical Functions**: provides math functions: linear algebra, stats, Fourier transforms, random numbers, and more;
- **Interoperability**: arrays integrate smoothly with Pandas, Scipy, Matplotlib, and scikit-learn;
- **Vectorization**: enables efficient element-wise operations via vectorization, reducing the need for explicit loops.

## Why is this course included in the track?

Data scientists need to know `numpy` because it provides a **foundation for many essential data science tasks**. 

A solid grasp of NumPy empowers data scientists for efficient data manipulation, numerical tasks, and collaboration with other libraries. NumPy's array ops and math functions are core to data science, a vital skill for Python data scientists.

### Example 

**Vectorization** in Python employs NumPy's efficient array operations, replacing explicit loops for faster, concise code. It's essential for efficient Data Science calculations.

import numpy as np
import time

# Create two matrices
matrix1 = np.random.rand(1000, 1000)
matrix2 = np.random.rand(1000, 1000)

# Element-wise multiplication using vectorization
start_time_vectorized = time.time()
result_vectorized = matrix1 * matrix2
end_time_vectorized = time.time()

# Element-wise multiplication using nested loops
start_time_loops = time.time()
result_loops = [[matrix1[i][j] * matrix2[i][j] for j in range(1000)] for i in range(1000)]
end_time_loops = time.time()

# Calculate execution times
execution_time_vectorized = end_time_vectorized - start_time_vectorized
execution_time_loops = end_time_loops - start_time_loops

print('Vectorization Time:', execution_time_vectorized)
print('Loop Time:', execution_time_loops)

We can see a **significant difference** in execution time! Also note how much code was used to operate with Numpy and a loop: one simple operation vs. a rather complex loop. Thus, the benefits of using Numpy are clear.

Here we will briefly describe all the courses on the track and consider how you can apply the gained knowledge in practice.

Preparation for Data Science Track Overview

Numpy in a Nutshell

Why do we need Numpy?

Why is this course included in the track?

Example