https://blog.anoff.io/tags/data-science/Recent content in Data Science on Andreas' BlogHugoenThu, 09 Apr 2026 00:00:00 +0000https://blog.anoff.io/2026-04-ai-my-stock-portfolio/Thu, 09 Apr 2026 00:00:00 +0000https://blog.anoff.io/2026-04-ai-my-stock-portfolio/<p>My stock portfolio is spread across multiple brokers in different countries — Japanese stocks with one broker, European positions with another, investment funds in a third account. Each has its own dashboard, export format, and way of presenting performance. Relying on these dashboards as my single source of truth felt uncomfortable. What if a broker changes its interface or suspends my account? How do I compare positions across currencies, time horizons, and purchase dates?</p> <p>I wanted <strong>local, inspectable, portable data ownership</strong> — files on my own disk that don&rsquo;t disappear if a broker changes policy. Not just the raw transaction records, but the <strong>analysis process itself</strong>.</p> <p>This post tells the story of how I built a suite of tools to solve that problem. But the real journey wasn&rsquo;t about writing Python scripts — it was about discovering <strong>how to think about stock performance</strong> in the first place. This was also a trial run in using AI end-to-end: <strong>Gemini</strong> for strategic thinking and high-level concepts, <strong>Claude</strong> and <strong>VS Code Copilot</strong> for implementation and debugging.</p>