Alex Molas
Work
Senior Data Scientist · Wallapop Sep 2023 - present
- Lead ML initiatives for the search team focusing on matching, ranking, and software best practices. Used Solr as the search engine.
- Refactored ETL from manual notebooks to Spark jobs. Reduced execution time from days to hours, improving the developer experience.
- Promoted modern practices within the team. Worked on a vector search PoC to estimate impact, risks, and costs.
- Experimented with synonym generation and typo correction. Used classical techniques and LLMs.
- Used LLMs and instructor to extract standardized attributes from user generated descriptions and user queries.
- Developed a library using Polars to analyze shadow tests. Allowed the developers to make complex analysis in local.
- Organized events to increase machine learning visibility: internal hackathons, Meetups, and conferences.
Senior Data Scientist · Stuart Nov 2019 - Sep 2023
- Improved ETA accuracy by +30% using a deep learning model. Achieved a +28% improvement in cold-start locations.
- Designed and developed pipelines to automatically train, evaluate, and deploy ETA models.
- Built a distributed pipeline to process daily all the events dumped from Kafka to S3.
- Designed an experimental dispatcher engine to solve the assignment problem using Python and OR-Tools.
- Planned a POC using LightGBM to estimate the probability of a courier accepting a specific delivery.
- Mentored a senior software engineer who wanted to specialize in machine learning and data science
Data Scientist · 21 Buttons Jun 2019 - Oct 2019
- Started a recommender system based on implicit user feedback to recommend similar profiles to users.
- Implemented a backend ML solution to classify clothes based on images and descriptions.
Data Scientist · Privalia (Veepee) May 2018 - Jun 2019
- Implemented an ML model to forecast clearance sales. Launched a pricing engine on top of the forecast model.
Data Analyst · Gauss&Neumann Oct 2017 - Feb 2018
- Developed tools for monitoring and optimizing SEM campaigns using Google AdWords and Python.
Projects
Publications & Talks & Popular Posts
- "A search engine in 80 lines of Python". Blog (2024).
- "Analyzing gender gap in chess". Blog (2023).
- "Choose the smallest number not chosen yet". Blog (2023).
- "How to beat your friends in fantasy football", PyDay ES 2022. Slides (2022).
- "Field theory for recurrent mobility". Nature Communications 10, 3895 (2019).
- "Streak Camera Calibration Using RF Switches". 5th IBIC, MOPG55 (2017).
- "Social network analysis of communities in literature" poster. Won the IFISC Best Poster Award.
Education
MSc. Physics for Complex Systems · CSIC-IFISC 2016-2017
- Got an IFISC Mobility Scholarship that covered my fees and year expenses during my studies.
- Won the best poster award and presented the results at the local radio station.
- Master thesis using field theory and data analysis to study recurrent mobility. Results were published in Nature Communications.
B. Sc. Physics · UAB 2012-2016
- Worked as an assistant professor in the subject of numerical methods.
- Internship at the ALBA synchrotron. Results were published at the 5th IBIC conference.
- Summer internship at IFAE. Worked on Yang-Mills theory simulations.
- Received a scholarship from the Spanish government every year for my academic achievements.