Student Lesson Python Libraries

What is a Library?

Essentially a list of pre-written code that you can use to streamline and clean up your program.

Libraries can help simplify complex programs

APIS are specifications for how the procedures in a library behave, and how they can be used

Documentations for an API/library is necessary in understanding the behaviors provided by the API/library and how to use them

Libraries that we will go over: Requests, Pillow, Pandas, Numpy, Scikit-Learn, TensorFlow, matplotlib.

Why use a Library?

A key part of coding is creating efficient and easy to read code for you and other developers.

Here are the tools we have so far:

Algorithms: Combining multiple statements to complete a specific task then outputs it
Iterations: Allows you to repeat a set of commands for each object in a list
Procedures: Combines code to complete a general task

All of these reduce code clutter, but what if you can get one line to achieve the same result as 15 lines of an algorithm?

For example, do you want to spend your time coding an elaborate system of iterations, nested loops, and complex procedures when you can use somebody else’s code?

Libraries can help you do that. It helps to simplify complex operations into a footnote, and makes your code look neat and easy to debug later.

For example…

How to use Libraries

First, we have to install them into VScode. We can’t use libraries if they are not available to use in the system.

After installing them, now you can use them in your code by importing. Here is a sample.

import math

# Get the square root of a number
number = 16
square_root = math.sqrt(number)

print(f"The square root of {number} is {square_root}")

Required Installations

Please run the following commands in your vscode terminal in order to continue the lesson

pip install numpy
pip install matplotlib
pip install scikit-learn
pip install pillow
pip install pandas
pip install tensorflow
pip install requests

Images using requests and pillow libraries

‘Requests’ is focused on handling HTTP requests and web data while ‘Pillow’ is designed for data manipulation and analysis It’s common to see them used together in data-related assignments where data is fetched by HTTP requests using Requests and then processed and analyzed with Pandas.

Here’s an example:

import requests
from PIL import Image
from io import BytesIO

# Step 1: Download an image using Requests
image_url = "https://example.com/path/to/your/image.jpg"  # Replace with your own URL of the image you want to download
response = requests.get(image_url)

if response.status_code == 200:
    # Step 2: Process the downloaded image using Pillow
    image_data = BytesIO(response.content)  # Create an in-memory binary stream from the response content
    img = Image.open(image_data)  # Open the image using Pillow

    # Perform image processing tasks here, like resizing or applying filters
    img = img.resize((x, y))  # Resize the image and replace x,y with desired amounts

    # Step 3: Save the processed image using Pillow
    img.save("processed_image.jpg")  # Save the processed image to a file

    print("Image downloaded, processed, and saved.")
else:
    print(f"Failed to download image. Status code: {response.status_code}")

In this code, we use the Requests library to download an image from a URL and then if the download is successful the HTTP status code 200 will pop up, and from there we create an in-memory binary stream (BytesIO) from the response content. We then use the Pillow library to open the image, make any necessary changes, and save the processed image to a file.

Here’s a step by step tutorial on how we wrote this code: 1)We started by importing the necessary libraries, which were Requests, Pillow, and io.

2)Download the Image

3)Use the Requests library to send an HTTP GET request to the URL to download the image. Check the response status code to make sure the download goes through(status code 200).

4)If the download is successful, create an in-memory binary stream (BytesIO) from the response content. Process the Image:

5)Utilize the Pillow library to open the image from the binary stream. Change photo to desired preference(ie: size) Save the Processed Image:

6)Save the processed image to a file using Pillow. Choose a filename and file format for the saved image.

Hack 1

Input an image url and put in youru desired size changes

import requests
from PIL import Image
from io import BytesIO

# Step 1: Download an image using Requests
image_url = "https://example.com/path/to/your/image.jpg"  # Replace with the actual URL of the image you want to download
response = requests.get(image_url)

if response.status_code == 200:
    # Step 2: Process the downloaded image using Pillow
    image_data = BytesIO(response.content)  # Create an in-memory binary stream from the response content
    img = Image.open(image_data)  # Open the image using Pillow

    # Perform image processing tasks here, like resizing or applying filters
    img = img.resize((x, y))  # Resize the image and replace x,y with desired amounts

    # Step 3: Save the processed image using Pillow
    img.save("processed_image.jpg")  # Save the processed image to a file

    print("Image downloaded, processed, and saved.")
else:
    print(f"Failed to download image. Status code: {response.status_code}")

Failed to download image. Status code: 404

Math Operations With Python Libraries

Numpy(Numerical Python) is used for numerical and scientific computing. It provides tools for handling large sets of numbers, such as data tables and arrays. Numpy makes it easier and more efficient to do mathematical tasks.

The Matplotlib library lets you create a visual representation of your data (graphs, charts, and etc.)

Example Sine Graph

Uses numpy and matplotlib libaries

import numpy as np
import matplotlib.pyplot as plt

# Generate sample data with NumPy
x = np.linspace(0, 2 * np.pi, 100) 
# Create an array of values from 0 to 2*pi
# 100 is included to have 100 points distributed between 0 and 2π to make graph smoother
y = np.sin(x)
# Compute the sine of each value

# Create a simple line plot using Matplotlib
plt.plot(x, y, label='Sine Function', color='blue', linestyle='-')  # Create the plot
plt.title('Sine Function')  # Set the title
plt.xlabel('x')  # Label for the x-axis
plt.ylabel('sin(x)')  # Label for the y-axis
plt.grid(True)  # Display a grid
plt.legend()  # Show the legend
plt.show()  # Display the plot

png

Hack 2

Using the data from the numpy library, create a visual graph using different matplotlib functions.

import numpy as np
import matplotlib.pyplot as plt

# Generate data for two lines
x = np.linspace(0, 10, 50)  # Create an array of values from 0 to 10
y1 = 2 * x + 1  # Set of data poits

# Create and display a plot using Matplotlib

# your code here

Tensor Flow is used in deep learning and neural networks, while scikit-learn is used for typical machine learning tasks. When used together, they can tackle machine learning projects. In the code below, Tensor Flow is used for model creation and training. Scikit-learn is used for data-processing and model evaluation.

Pip install tensorflow scikit-learn

import numpy as np
import tensorflow as tf
from sklearn.model_selection import train_test_split
from sklearn.metrics import mean_squared_error
from sklearn.preprocessing import StandardScaler
from tensorflow import keras
from tensorflow.keras import layers
# Generate synthetic data
np.random.seed(0)
X = np.random.rand(100, 1)  # Feature
y = 2 * X + 1 + 0.1 * np.random.randn(100, 1)  # Target variable with noise
# Split the data into training and testing sets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)
# Standardize the features
scaler = StandardScaler()
X_train = scaler.fit_transform(X_train)
X_test = scaler.transform(X_test)
# Create a simple linear regression model using TensorFlow and Keras
model = keras.Sequential([
    layers.Input(shape=(1,)),
    layers.Dense(1)
])
# Compile the model
model.compile(optimizer='adam', loss='mean_squared_error')
# Train the model
model.fit(X_train, y_train, epochs=100, batch_size=32, verbose=2)
# Make predictions on the test set
y_pred = model.predict(X_test)
# Calculate the Mean Squared Error on the test set
mse = mean_squared_error(y_test, y_pred)
print(f"Mean Squared Error: {mse:.4f}")

---------------------------------------------------------------------------

ModuleNotFoundError                       Traceback (most recent call last)

Cell In[12], line 1
----> 1 import numpy as np
      2 import tensorflow as tf
      3 from sklearn.model_selection import train_test_split


ModuleNotFoundError: No module named 'numpy'

A decrease in loss and time metrics (ms/epoch and ms/step) shows the efficiency increases as the training epochs increases

Hack 3

fill in the missing code to match the custom data set

import numpy as np
import tensorflow as tf
from sklearn.model_selection import train_test_split
from sklearn.metrics import mean_squared_error
from sklearn.preprocessing import StandardScaler
from tensorflow import keras
from tensorflow.keras import layers
# Generate a custom dataset (replace this with your data loading code)
# Synthetic data: House prices based on number of bedrooms and square footage
np.random.seed(0)
num_samples = 100
bedrooms = np.random.randint(1, 5, num_samples)
square_footage = np.random.randint(1000, 2500, num_samples)
house_prices = 100000 + 50000 * bedrooms + 100 * square_footage + 10000 * np.random.randn(num_samples)
# Combine features (bedrooms and square footage) into one array
X = np.column_stack((bedrooms, square_footage))
y = house_prices.reshape(-1, 1)
# Split the data into training and testing sets

# Standardize the features

# Create a regression model using TensorFlow and Keras

    # Input shape adjusted to the number of features
     # Output layer for regression

# Compile the model for regression
  # Using MSE as the loss function
# Train the model

# Make predictions on the test set

# Calculate the Mean Squared Error on the test set

HOMEWORK 1

Create a GPA calculator using Pandas and Matplot libraries and make: 1) A dataframe 2) A specified dictionary 3) and a print function that outputs the final GPA

Extra points can be earned with creativity.

# your code here

Original Price: $100.00
Discount Percentage: 20.0%
Discounted Price: $80.00

HOMEWORK 2

Import and use the “random” library to generate 50 different points from the range 0-100, then display the randomized data using a scatter plot.