wget https://raw.githubusercontent.com/aidenhuynh/CS_Swag/master/_notebooks/2022-11-30-randomvalues.ipynb

Libraries

  • A library is a collection of precompiled codes that can be used later on in a program for some specific well-defined operations.
  • These precompiled codes can be referred to as modules. Each module contains bundles of code that can be used repeatedly in different programs.
  • A library may also contain documentation, configuration data, message templates, classes, and values, etc.

Why are libraries important?

  • Using Libraries makes Python Programming simpler and convenient for the programmer.
  • One example would be through looping and iteration, as we don’t need to write the same code again and again for different programs.
  • Python libraries play a very vital role in fields of Machine Learning, Data Science, Data Visualization, etc.

A few libraries that simplify coding processes:

  • Pillow allows you to work with images.
  • Tensor Flow helps with data automation and monitors performance.
  • Matplotlib allows you to make 2D graphs and plots.

The AP Exam Refrence Sheet itself is a library! Screenshot 2022-12-11 221853

Hacks:

Research two other Python Libraries NOT DISCUSSED DURING LESSON and make a markdown post, explaining their function and how it helps programmers code.

API’s

  • An Application Program Interface, or API, contains specific direction for how the procedures in a library behave and can be used.
  • An API acts as a gateway for the imported procedures from a library to interact with the rest of your code.

Activity: Walkthrough with NumPy

  • Install NumPy on VSCode:
    1. Open New Terminal In VSCode:
    2. pip3 install --upgrade pip
    3. pip install numpy

REMEMBER: When running library code cells use Python Interpreter Conda (Version 3.9.12)

Example of using NumPy for arrays: 

import numpy as np
new_matrix = np.array([[1, 2, 3],[4, 5, 6],[7, 8, 9]])
 
print (new_matrix)

[[1 2 3]
 [4 5 6]
 [7 8 9]]

Example of using NumPy for derivatives: 

import numpy as np
 
# defining polynomial function
var = np.poly1d([2, 0, 1])
print("Polynomial function, f(x):\n", var)
 
# calculating the derivative
derivative = var.deriv()
print("Derivative, f(x)'=", derivative)
 
# calculates the derivative of after
# given value of x
print("When x=5  f(x)'=", derivative(5))

Random Values

  • Random number generation (RNG) produces a random number (crazy right?)
    • This means that a procedure with RNG can return different values even if the parameters (inputs) do not change
  • CollegeBoard uses RANDOM(A, B), to return an integer between integers A and B.
    • RANDOM(1, 10) can output 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10
    • In Python, this would be random.randint(A, B), after importing Python's "random" library (import random)
    • JavaScript's works a little differently, with Math.random() returning a value between 0 and 1.
      • To match Python and CollegeBoard, you could make a procedure like this

CollegeBoard Example: What is the possible range of values for answ3

CollegeBoard

Convert the following procedure to Python, then determine the range of outputs if n = 5. 


PROCEDURE Dice(n)
    sum ← 0
    REPEAT UNTIL n = 0
        sum ← sum + RANDOM(1, 6)
        n ← n - 1
    RETURN sum


import random # Fill in the blank

def Dice(n):
    # Code here
    
    Dice(5) # Will output a range of __ to __
    return

Research Hacks

TensorFlow

TensorFlow is a python library that is used for numerical computation that makes machine learning and developing neural networks faster and easier. These computations are expressed as dataflow graphs.

Pandas

Pandas is a python library that is used for data analysis. It is built on matplotlib for data visualization and numpy for mathematical operations. Pandas allows use of many of both these libraries methods while using less code.

Homework

  1. Write a procedure that generates n random numbers, then sorts those numbers into lists of even and odd numbers (JS or Python, Python will be easier).

  2. Using NumPy and only coding in python cell, find the answer to the following questions: a. What is the derivative of 2x^5 - 6x^2 + 24x? b. What is the derivative of (13x^4 + 4x^2) / 2 when x = 9?

  3. Suppose you have a group of 10 dogs and 10 cats, and you want to create a random order for them. Show how random number generation could be used to create this random order.

import random

# Asks the user to enter the number of numbers to generate
n = int(input("How many numbers do you want to generate? "))

# Asks the user to enter the min and max for the random numbers
min = int(input("Enter the minimum number: "))
max = int(input("Enter the maximum number: "))

# Generates a list of random numbers for the range
numbers = [random.randint(min, max) for _ in range(n)]

# Sorts the numbers into even and odd lists
evens = [n for n in numbers if n % 2 == 0]
odds = [n for n in numbers if n % 2 != 0]

# Print the lists
print(evens)
print(odds)

[8, 6, 12]
[11, 9, 9, 3, 11]

import numpy as np

# Define the polynomial
poly = np.array([13, 0, 4, 0, 0])

# Calculate the derivative
derivative = np.polyder(poly)

# Define result
result = np.polyval(derivative, 9)

# Print
print(result)

37980

import numpy as np

# Define the polynomial
poly = np.poly1d([2, 0, -6, 24, 0])

# Calculate the derivative
derivative = np.polyder(poly)

# Print the derivative
print(derivative)

   3
8 x - 12 x + 24

import random 

cats = ["cat" + str(i) for i in range(10)] # makes cat1, cat2... in list by adding the num from range to a index
dogs = ["dog" + str(i) for i in range(10)] # makes dog1, dog2... in list by adding the num from range to a index

pets = cats + dogs # adds the lists together

random.shuffle(pets) # shuffles the pets list 

print(pets)

['cat1', 'dog4', 'dog1', 'cat0', 'dog8', 'cat5', 'dog0', 'dog5', 'cat3', 'dog9', 'dog3', 'cat2', 'dog6', 'cat4', 'cat7', 'dog2', 'cat9', 'cat6', 'cat8', 'dog7']