Building a Graph-Based Product to Predict Stock Prices using Machine Learning

MaFisher
11 min readMar 24, 2023

*Note: This is not financial advice and is purely for research purposes

Building a Graph-Based Product to Predict Stock Prices using Machine Learning

Predicting stock prices is a complex problem that can be solved using machine learning algorithms and graph-based visualization techniques. In this tutorial, we’ll walk you through the steps involved in building a graph-based product to help you predict when to buy a stock.

Step 1: Pull Real-Time Stock Data

To pull real-time stock data, we’ll use an API such as the Alpha Vantage API, which provides free access to real-time and historical stock data. We’ll use Python’s requests library to make an HTTP GET request to the API endpoint, passing in the function name (GLOBAL_QUOTE), the stock symbol (AAPL), and our API key as parameters. The response is in JSON format, which we can parse using the json() method of the response object.

To get started, you can sign up for a free API key from Alpha Vantage by following the instructions on their website: https://www.alphavantage.co/support/#api-key

Once you have your API key, you can use the following code snippet to pull real-time stock data:

import requests

api_key = 'YOUR_API_KEY'
symbol = 'AAPL'

url = f'https://www.alphavantage.co/query?function=GLOBAL_QUOTE&symbol={symbol}&apikey={api_key}'
response = requests.get(url)
data = response.json()['Global Quote']

open_price = float(data['02. open'])
high_price = float(data['03. high'])
low_price = float(data['04. low'])
volume = int(data['06. volume'])

In this code snippet, we first import the requests library. We then replace YOUR_API_KEY with your actual API key, and AAPL with the stock symbol you want to retrieve data for. We construct the API URL by passing in the function name, symbol, and API key as parameters, and make an HTTP GET request to the API endpoint using requests.get(). We then parse the JSON response using the json() method of the response object, and extract the relevant data fields such as the open price, high price, low price, and volume using the data[] dictionary.

Once you have the real-time stock data, you can combine it with historical stock data to train a machine learning model and make predictions.

Step 2: Preprocess the Data and Train a Machine Learning Model

Once we have the real-time stock data, we’ll combine it with historical stock data to train a machine learning model. We’ll use a supervised learning algorithm such as random forest regression or LSTM neural network to predict stock prices. We’ll preprocess the data by creating a new column to indicate whether the stock price went up or down, and then split the data into training and testing sets.

We’ll use Python’s pandas library to load the historical stock data from a CSV file and combine it with the real-time data. We'll create a new column in the combined dataset called Change to indicate whether the stock price went up or down. We'll then drop the rows with missing values since the diff() method creates a NaN value for the first row. We'll use Python's scikit-learn library to split the data into training and testing sets, and fit the machine learning model to the training data using the fit() method.

import pandas as pd
from sklearn.ensemble import RandomForestRegressor
from sklearn.model_selection import train_test_split

historical_data = pd.read_csv('historical_data.csv')
historical_data = historical_data.drop(columns=['Date', 'Adj Close'])

data = pd.DataFrame({
'Open': [open_price],
'High': [high_price],
'Low': [low_price],
'Volume': [volume]
})

combined_data = pd.concat([historical_data, data])

combined_data['Change'] = combined_data['Close'].diff().shift(-1)
combined_data.loc[combined_data['Change'] > 0, 'Change'] = 1
combined_data.loc[combined_data['Change'] < 0, 'Change'] = 0
combined_data = combined_data.dropna()

features = ['Open', 'High', 'Low', 'Volume']
X_train, X_test, y_train, y_test = train_test_split(combined_data[features], combined_data['Change'], test_size=0.2)

model = RandomForestRegressor(n_estimators=100)
model.fit(X_train, y_train)

In this code snippet, we first import the necessary libraries,ncluding pandas for working with data, RandomForestRegressor for the machine learning model, and train_test_split for splitting the data into training and testing sets. We load the historical data from a CSV file, and drop the columns that we don't need. We then create a new DataFrame with the real-time data, and concatenate it with the historical data using pd.concat(). We create a new column in the combined dataset called Change to indicate whether the stock price went up or down. We use the diff() method to calculate the difference between consecutive values, and the shift() method to shift the values by one row. We then replace the positive and negative values with 1 and 0, respectively, using loc[]. Finally, we drop the rows with missing values using dropna(), and split the data into training and testing sets using train_test_split(). We fit the machine learning model to the training data using model.fit().

Step 3: Create a Graph to Visualize the Data

Once we have trained our machine learning model and made predictions on the testing data, we can use the predicted values to create a graph and visualize the performance of our model. We’ll use Python’s matplotlib library to create a line graph of the actual and predicted stock price changes.

import matplotlib.pyplot as plt

predictions = model.predict(X_test)

plt.plot(y_test.values, label='Actual')
plt.plot(predictions, label='Predicted')

plt.legend()
plt.xlabel('Time')
plt.ylabel('Stock Price Change')
plt.show()

In this code snippet, we first import the matplotlib library. We then make predictions on the testing data using model.predict(). We create a line graph of the actual and predicted stock price changes using plt.plot(). We add a legend and axis labels using plt.legend(), plt.xlabel(), and plt.ylabel(). Finally, we show the graph using plt.show().

Step 4: Incorporate the Machine Learning Component into Your Product

Sure, here’s a rewritten version of Step 4 with links and code snippets:

Step 4: Incorporate the Machine Learning Component into Your Product

To incorporate a machine learning component into your product, you can create a script that runs periodically to pull real-time stock data, preprocess the data, and make predictions using your machine learning model. You can then use the predictions to determine when to buy or sell the stock and send alerts to your users.

However, building a robust machine learning system involves several additional steps beyond simply training a model and making predictions. Here are some additional steps you can take to ensure that your machine learning system is reliable, scalable, and secure:

  1. Data Collection: Collecting and storing data in a reliable and secure way is critical to the performance and reliability of your machine learning system. Make sure that your data collection process is automated, and that the data is stored in a centralized database or data warehouse that is designed for scalability and reliability. You can use tools such as Apache Kafka and Apache Spark to collect and process large volumes of data in real-time.

Here’s an example code snippet for collecting real-time stock data using Alpha Vantage API and storing it in a MongoDB database:

import requests
import pymongo

api_key = 'YOUR_API_KEY'
symbol = 'AAPL'

url = f'https://www.alphavantage.co/query?function=GLOBAL_QUOTE&symbol={symbol}&apikey={api_key}'
response = requests.get(url)
data = response.json()['Global Quote']

open_price = float(data['02. open'])
high_price = float(data['03. high'])
low_price = float(data['04. low'])
volume = int(data['06. volume'])

client = pymongo.MongoClient('mongodb://localhost:27017/')
db = client['stocks']
collection = db['AAPL']
collection.insert_one({
'open_price': open_price,
'high_price': high_price,
'low_price': low_price,
'volume': volume
})

In this code snippet, we first import the requests library to make an HTTP GET request to the Alpha Vantage API endpoint, passing in our API key and stock symbol as parameters. We then parse the JSON response using the json() method of the response object, and extract the relevant data fields such as the open price, high price, low price, and volume using the data[] dictionary. Finally, we use the pymongo library to connect to a MongoDB database running on localhost and insert the data into a collection named AAPL.

  1. Data Preprocessing: Preprocessing the data is an important step to ensure that the data is in a suitable format for training the machine learning model. You may need to clean the data by removing outliers, missing values, and duplicates, and transform the data by scaling, normalizing, or encoding it. You can use tools such as pandas, NumPy, and scikit-learn to preprocess the data.

Here’s an example code snippet for preprocessing stock data using pandas and scikit-learn:

import pandas as pd
from sklearn.preprocessing import StandardScaler

client = pymongo.MongoClient('mongodb://localhost:27017/')
db = client['stocks']
collection = db['AAPL']

df = pd.DataFrame(list(collection.find()))
df.set_index('_id', inplace=True)
df.drop(['symbol', 'date'], axis=1, inplace=True)

scaler = StandardScaler()
df_scaled = pd.DataFrame(scaler.fit_transform(df), columns=df.columns)

In this code snippet, we first import the pandas library to load the data from the MongoDB collection into a DataFrame. We then use the set_index() method to set the _id field as the index of the DataFrame, and drop the symbol and date fields since they are not needed for training the machine learning model. Finally, we use the StandardScaler() class from scikit-learn to scale the data to have a mean of 0 and standard deviation of 1, which can improve the performance of some machine learning algorithms.

  1. Model Training: Training the machine learning model involves selecting the appropriate algorithm, feature engineering, and hyperparameter tuning. You may need to experiment with different algorithms and techniques, and use cross-validation to evaluate the performance of the model. You can use tools such as scikit-learn, TensorFlow, and PyTorch to train the model.

Here’s an example code snippet for training a linear regression model using scikit-learn:

from sklearn.linear_model import LinearRegression
from sklearn.model_selection import train_test_split

X = df_scaled.drop('close_price', axis=1)
y = df_scaled['close_price']

X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)

model = LinearRegression()
model.fit(X_train, y_train)

In this code snippet, we first split the preprocessed data into training and test sets using the train_test_split() function from scikit-learn. We then define the input features X as all columns except the target variable close_price, and the target variable y as close_price. Finally, we create a LinearRegression() model object and fit it to the training data using the fit() method.

  1. Model Deployment: Deploying the machine learning model involves integrating it into your product, and making it available for prediction. You may need to package the model as a REST API, Docker container, or serverless function, and deploy it to a cloud-based platform such as AWS, Azure, or Google Cloud. You can use tools such as Flask, FastAPI, and TensorFlow Serving to deploy the model.

Here’s an example code snippet for deploying a machine learning model as a REST API using Flask:

from flask import Flask, request, jsonify
import joblib

app = Flask(__name__)
model = joblib.load('model.joblib')

@app.route('/predict', methods=['POST'])
def predict():
data = request.get_json()
prediction = model.predict(data['X'])
return jsonify({'prediction': prediction.tolist()})

if __name__ == '__main__':
app.run(debug=True)

In this code snippet, we first import the Flask class from Flask, and the joblib library from scikit-learn to load the trained machine learning model from a file named model.joblib. We then define a predict() function that takes a JSON request containing the input features X, and returns a JSON response containing the predicted target variable. Finally, we use the run() method of the Flask object to start the Flask server.

  1. Monitoring and Maintenance: Monitoring and maintaining the machine learning system is critical to ensure that it continues to perform well over time. You may need to monitor the performance of the model, track the quality of the predictions, and retrain the model periodically to account for changes in the data or the environment. You can use tools such as Prometheus, Grafana, and Kibana to monitor and visualize the performance of the system.

Incorporating machine learning components into your product can be made easier by leveraging cloud provider services, such as those offered by Azure. Azure offers services such as Azure Machine Learning for building and training machine learning models, Azure Functions for deploying serverless functions, and Azure Monitor for monitoring and logging.

Building a machine learning system that accurately predicts stock prices requires expertise in both finance and machine learning. It’s essential to evaluate the performance of the system using appropriate metrics and to seek expert advice if necessary. Additionally, it’s essential to consider the ethical implications of using machine learning to predict stock prices and to ensure that the system is transparent and accountable to its users.

In summary, building a graph-based product to help predict the right time to buy a stock requires several steps, including collecting real-time and historical stock data, visualizing the data using graph databases, training a machine learning model to make predictions, and incorporating the machine learning component into your product. By following best practices for each of these steps and leveraging Azure services, you can build a robust and reliable machine learning system that provides value to your users.

Conclusion

In this tutorial, we’ve shown you how to build a graph-based product to help you predict when to buy a stock using machine learning algorithms and graph-based visualization techniques. We’ve covered how to pull real-time stock data using an API, preprocess the data, train a machine learning model, create a graph to visualize the data, and incorporate the machine learning component into your product. With these techniques, you can build a powerful tool to help you make informed decisions about when to buy or sell a stock. By constantly monitoring the stock prices and using machine learning algorithms to make predictions, you can improve your chances of making profitable trades.

To improve the performance of our machine learning model, we can try using different algorithms, feature engineering, and hyperparameter tuning. We can also incorporate more data sources, such as news articles and social media sentiment, to capture the impact of events on the stock prices. We can use natural language processing techniques to extract relevant information from the textual data, and combine it with the numerical data to train a more accurate model.

We can also enhance the graph-based visualization by adding interactive features, such as zooming, panning, and highlighting. We can use JavaScript libraries such as D3.js and Plotly.js to create interactive and responsive graphs that allow users to explore the data and gain insights. We can also use machine learning algorithms such as clustering and anomaly detection to identify patterns and anomalies in the data, and visualize them using heat maps and scatter plots.

In addition to predicting stock prices, we can also use the same techniques to predict other financial metrics such as revenue, earnings, and market capitalization. We can apply machine learning algorithms such as linear regression and time series forecasting to these metrics and create graphs to visualize their trends over time. By combining the predictions of multiple metrics, we can create a holistic view of a company’s financial health and make more informed investment decisions.

However, it’s important to remember that predicting stock prices is a highly uncertain task, and there are many factors that can influence the performance of your model. Economic and political events, changes in consumer behavior, and unexpected market fluctuations can all affect the stock prices and render your predictions inaccurate. Therefore, it’s crucial to use a combination of different tools and approaches, such as fundamental analysis, technical analysis, and market sentiment analysis, to complement your machine learning model and reduce the risk of making poor investment decisions.

Another important consideration when building a graph-based product to predict stock prices is data privacy and security. The real-time stock data and user information that you collect must be stored and processed in compliance with relevant laws and regulations, such as the General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA). You must also implement robust security measures, such as encryption and access controls, to prevent unauthorized access or breaches of sensitive data.

To ensure the long-term success of your graph-based product, it’s crucial to establish a feedback loop with your users and gather their feedback on the usability and effectiveness of your product. By analyzing the user behavior and preferences, you can identify areas for improvement and implement changes that enhance the user experience and increase the adoption of your product.

In conclusion, building a graph-based product to predict stock prices is a complex and challenging task that requires a combination of technical, domain, and user experience skills. By following the best practices outlined in this tutorial, and constantly experimenting and improving your machine learning model and graph-based visualization, you can create a powerful tool that helps you stay ahead of the market and make informed investment decisions.

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MaFisher

Building something new // Brown University, Adjunct Staff