Stock trading bot

During my senior year of high school, my economics class had a competition where we traded stocks on a fake online exchange. I wrote a Python shell script which could make purchasing decisions for me, and submit them to the website. It uses Beautiful Soup to log in to the virtual exchange with my details, and to collect stock information from sources like Yahoo Finance. When given a budget, it chooses a diverse selection of shares which most closely approaches the budget without exceeding it.

Challenges

Using web scraping to collect data online is difficult to do performantly and robustly. Network errors and slow internet speeds caused the program to run very slowly, and changes to page layouts could cause the scraper to err. To solve these errors, a script can query several pages in parallel and retry on network errors. Caching can also significantly speed things up. I chose Yahoo Stocks because its page layout changes very little over time, and I use BeautifulSoup, a very robust HTML parser and scraper to reliably retrieve data.