Numpy Introduction Lecture

Introduction to Numpy

• Numpy is a powerful library in Python used for numerical computations.
• Comparable to lists in Python but significantly faster.
• List can perform similar tasks but are slower.
• Numpy arrays are up to 50 times faster than Python lists.
• Preferred for processing due to speed and efficiency.

Key Features of Numpy

• Contiguous Memory Allocation:

  • Unlike lists, Numpy arrays are stored in continuous memory locations.
  • This continuous storage leads to quicker access and manipulation.
  • Example: In a list, elements are stored at varied memory addresses requiring additional access steps.
  • In Numpy, knowing the memory address of the first element allows direct access to subsequent elements.

• Implemented in Multiple Languages:

  • Primarily written in Python but core parts requiring fast computation are written in C and C++.
  • This multi-language approach aids in achieving high performance.

Coding with Numpy

Basic Code Structure

• To use Numpy, it needs to be imported in the code:

  import numpy as np
  

  This command lets the computer know that Numpy library functions will be used.
• Example of creating an array:

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

  • np.array() creates an array with the given elements.
  • Printing arr will display the array elements.

Aliases and Shortcuts

• Large names like numpy can be alias to shorten and simplify the code.
• By using import numpy as np,
  • np becomes a shorthand to reference the Numpy library.
  • Example: np.array() instead of numpy.array().

Checking Version

• To check the version of the Numpy library used:

  print(np.__version__)
  

  • This gives the installed version of Numpy.

Conclusion

• Numpy is a critical tool in Python for efficient numerical computations due to its speed and continuous memory storage and its multi-language implementation.
• Understanding and utilizing Numpy's functions is essential for efficient coding in data processing and scientific computation tasks.