# Sylvain Lesage (@rednegra.net)

Profile: https://sifa.id/p/rednegra.net
Headline: Senior software engineer - frontend / data / geospatial
Location: Rennes, Bretagne, France

## About

👋 Hi, I'm Sylvain Lesage. I have a background in data science, data visualization, and web development, and I love creating interactive visualizations, advanced graphical tools, and data-driven applications.

​

To help you skim my past works:

​

☆☆☆ now: Data-driven frontend development (freelance) ☆☆☆

​

Before:

🔸2021 ⇢ 2024: Software development and data engineering at 🤗 Hugging Face

🔸2018 ⇢ 2021: Data analysis and visualization (freelance)

🔸2009 ⇢ 2018: Web development + e-government, Bolivia 🇧🇴

🔸2003 ⇢ 2009: PhD in machine learning + scientific computing for industry

## Career

- **Datavisualization and software developer at Sylvain Lesage Dataviz** (Sep 2024 - Present)
  Hyperparam development of open source React components and apps (React, TypeScript, CSS Modules, Next.js, Parquet)  FusedLabs efficient fetching and visualization of table data and charts (hyparquet, hightable, Mosaic, DuckDB, vgplot, React, TypeScript, Next.js)  Source Cooperative development of open source React components (React, TypeScript, Next.js, OpenLayers)  Jason Forrest Agency migration of an interactive map from D3.js to MapLibre (D3.js, MapLibre, React)  Migreurop development of a static website, with an interactive map of manifestations and resources for migrants in Europe (Astro, TypeScript, Tailwind CSS, Leaflet)  private client preparation of a virtual machine image for geocoding Brazilian addresses with Pelias (Pelias, Docker, VirtualBox, Vagrant, Linux)  Cartes.app (volunteer) contribution to the internationalization and development of an open source Google Maps alternative (React, TypeScript, Next.js, MapLibre, Lingui, Weblate)
- **Part-time Software Engineer at Hugging Face** (Sep 2024 - Present)
  Remote
  Helping with the Dataset Studio on the Hugging Face Hub (Python, Node.js, Svelte)
- **Software Engineer at Hugging Face** (Jun 2021 - Sep 2024)
  Building the dataset viewer in the Hugging Face Hub, for >200k datasets (Python, MongoDB, Node.js, Svelte, Helm/Kubernetes)
- **Datavisualization and software developer at Sylvain Lesage Dataviz** (Jun 2019 - Jun 2021)
  \+ for LIRIS laboratory: development of data-visualization web applications and prototypes (JavaScript, Observable notebooks, D3.js, video, Svelte, Vue.js, three.js) + for Le Monde Diplomatique: consulting on data administration + for MAbSilico: SaaS architecture design, software development (Node.js, TypeScript, Vue.js, PostgreSQL) + for PublicEye: data analysis and descriptive statistics (R, JavaScript) + small gigs on Upwork: D3.js animation, geocoder setup, data scraping
- **Datavisualization and software developer at Sylvain Lesage Dataviz** (Jan 2019 - Jun 2019)
  \+ for PublicEye: data analysis and production of statistics (R), map design and web application (JavaScript, D3.js)
  \- selected in the Sigma Awards 2020 shortlist (https://datajournalism.com/awards) + for Camptocamp SA: features development and bug fixing on geOrchestra (Java, maven, docker) + publication of JavaScript notebooks on ObservableHQ
- **Founder, datavisualization developer at 3600.lat** (Aug 2018 - Dec 2018)
  \+ for Moritz Stefaner and the EigenFactor project: port of a Flash application to a web application, with Philippe Rivière (JavaScript, D3.js) + JavaScript notebooks
- **Teacher at Escuela Militar de Ingeniería** (May 2018)
  \+ "Relational databases security" course in Master in Information Technologies Security (PostgreSQL, Spanish).
- **Head of Innovation, Research and Development Unit at Agetic Bolivia** (Oct 2017 - Mar 2018)
  \+ project management on public administration simplification and e-government + technical assessment and redaction of technical reports + redaction of public regulation and standardization texts + facilitation of working groups on technical standards in the Bolivian public administration + unit size: 35-40 persons
- **Executive director at Adsib** (Sep 2015 - Oct 2017)
  \+ decision-making on strategy, finances, public administration and technical projects + executive direction of services: country-level top level domain .bo (ccTLD, DNS), and launch of the first certification authority in Bolivia (digital signing, PKI) + redaction and negotiations on the National e-government plan + redaction and negotiations on the National free software and open standards implementation plan + Representation of ADSIB in COPLUTIC, the Bolivian national committee in charge of the public policies and strategies of the sector + agency size: 25-40 persons
- **Head of Innovation and Development Unit at Adsib** (May 2014 - Sep 2015)
  \+ project management and technical lead of the Innovation and Development Unit + technical design and implementation of the public certification authority (PKI, digital signature) + technical design and supervision of the installation works of a new datacenter + unit size: 5-10 persons
- **Teacher at Universidad Católica Boliviana San Pablo** (Mar 2015 - Jun 2015)
  \+ "Digital signal processing" semester course for Telecommunication and Mechatronics degrees.
- **Web developer at Bolivian mission to the UN** (May 2013 - Mar 2014)
  Geneva, CH
  \+ development of an institutional archive system (PHP, MySQL) + support and assessment to diplomats on telecommunications, science, and digital matters
- **Software developer at Freelance** (Jun 2013 - Dec 2013)
  Gaillard, FR
  \+ for Camptocamp SA: features development and bug fixing on geOrchestra (Java, JavaScript, OpenLayers, ExtJS, LDAP)
- **Technical lead at Vicepresidencia del Estado Plurinacional de Bolivia** (Dec 2011 - Feb 2013)
  \+ project management and technical lead of GeoBolivia, the Bolivian national spatial data infrastructure + technical design, development and installation (geOrchestra, GeoServer, GeoNetwork, PostgreSQL) + server and network administration (Debian, Tomcat, Apache, Postfix, DNS, LDAP) + redaction and facilitation of working groups on technical standards for GIS free software, web services and open data adoption in the Bolivian state. + unit size: 10-15
- **Teacher at Higher University of San Andrés** (Oct 2012 - Nov 2012)
  \+ "Free software for spatial data" for the Master in free software (QGis, OpenLayers, GeoServer, PostGIS)
- **Technical consultant at Adsib** (Oct 2011 - Nov 2011)
  \+ redaction of a report with technical recommendations for the creation of a certification authority (PKI, digital signature)
- **Web developer at Vicepresidencia del Estado Plurinacional de Bolivia** (Sep 2010 - Sep 2011)
  \+ development of an internal web tool on economics information (PHP, MySQL) + development of the institution website (PHP, SPIP, MySQL) + development of an electoral atlas of Bolivia (PHP, GeoServer, PostgreSQL, OpenLayers) + servers and networks administration (Debian, web, mail, DNS, LDAP)
- **Web developer at Administradora Boliviana de Carreteras** (Nov 2009 - May 2010)
  \+ development of the institution website (PHP, SPIP, MySQL, jQuery) + development of a web map on Bolivian roads trafficability condition (PostGIS, GeoServer, OpenLayers, Python) + installation of a free software streaming solution for opening of envelopes transparency (Icecast, ffmpeg) + servers and networks administration (Debian, web, mail, DNS, databases)
- **Linux digital TV developer at Sipradius** (Aug 2009 - Sep 2009)
  \+ add IP frames encapsulation in DVB frames to dvbnet Linux library (C, Wireshark) + server administration
- **Scientific developer at acsystème** (Oct 2007 - Feb 2009)
  \+ car industry: simulation of a shock absorbers system, minimization of escape pollution, detection of wheel rotation direction from sensor signals (Matlab, Simulink, C++) + power plant: data visualization, simulation and optimization of the electricity production (Matlab) + food: computer vision and automatic classification of fish species, simulation and optimization of fish cans filling (Matlab, Simulink) + battery: simulation to specify motor and battery characteristics in a electric bicycle design (Matlab, Simulink) + software development: Matlab extensions to generate reports, functions for Simulink + teaching on Matlab
- **Software developer at Kerlink** (Aug 2007 - Oct 2007)
  \+ development of a Linux driver for Cirrus CS42L51 audio codec (C, cross-compilation)
- **Teacher assistant at Université de Rennes** (Oct 2003 - Sep 2006)
  \+ "Functional analysis" course, and support classes in mathematics + "Matlab" course and practices + "C++" course and practices + internship mentoring

## Skills

### Technical
- Accessibility
- C++
- Cascading Style Sheets (CSS)
- D3.js
- Data Analysis
- Data Engineering
- Data Science
- Docker Products
- Git
- HTML
- Java
- JavaScript
- Kubernetes
- LaTeX
- Linux
- Machine Learning
- MATLAB
- MongoDB
- Next.js
- Node.js
- PHP
- Python
- Python (Programming Language)
- R
- React.js
- REST APIs
- Software Development
- Svelte
- Tailwind CSS
- TypeScript
- Vue.js
- Web Development
### Business
- Data Visualization
- Project Management
### Creative
- User Experience (UX)
### Interpersonal
- Spanish
### Security
- Network Administration
### Other
- Domain Name System (DNS)
- DuckDB
- E-government
- Geographic Information Systems (GIS)
- Legal Writing
- MapLibre
- Mosaic
- Observable
- Open-Source Software
- OpenLayers
- Parquet
- PKI
- Server Administration
- Signal Processing
- Three.js

## Projects

- **HighTable** (Oct 2024 - May 2026)
  HighTable is a React component created by Kenny Daniel for Hyperparam. It displays large datasets efficiently using virtual scroll. From 2024, I had the opportunity to become co-maintainer of the library, and I contributed to it by adding features like keyboard navigation, sort, rows selection, etc.
- **Datasets Server** (Sep 2021 - May 2026)
  Lightweight web API for visualizing and exploring all types of datasets
  \- computer vision, speech, text, and tabular
  \- stored on the Hugging Face Hub  https://github.com/huggingface/datasets-server/
- **Bolivian RIPE Atlas community** — https://atlas.tecnologia.bo/ (Nov 2017 - Nov 2018)
  \+ ambassador of RIPE Atlas probes program ("the largest Internet measurement network ever made"), distributing probes to volunteers in cities of Bolivia + presentations and workshops to help volunteers to install and use their probe

## Publications

- Datos personales, soluciones colectivas — Friedrich-Ebert-Stiftung Bolivia (Jul 2018) http://library.fes.de/pdf-files/bueros/bolivien/14659.pdf
- Shift-invariant dictionary learning for sparse representations: Extending K-SVD — 16th European Signal Processing Conference, 2008 (2008) http://ieeexplore.ieee.org/abstract/document/7080585/
- PhD thesis - Apprentissage de dictionnaires structurés pour la modélisation parcimonieuse des signaux multicanaux — Traitement du signal et de l'image. Université Rennes 1, 2007 (2007) https://hal.archives-ouvertes.fr/tel-00564061/
- MoTIF: An Efficient Algorithm for Learning Translation Invariant Dictionaries — IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP 2006, Toulouse, France, May 14-19, 2006 (Jul 2006) http://ieeexplore.ieee.org/abstract/document/1661411/
- Under-Determined Source Separation: Comparison of Two Approaches Based on Sparse Decompositions — Independent Component Analysis and Blind Signal Separation. ICA 2006. Lecture Notes in Computer Science, vol 3889. Springer, Berlin, Heidelberg (2006) https://link.springer.com/chapter/10.1007%2F11679363_79
- A survey of Sparse Component Analysis for blind source separation: principles, perspectives, and new challenges — ESANN'06 proceedings - 14th European Symposium on Artificial Neural Networks, Apr 2006, Bruges, Belgium (2006) https://hal.inria.fr/inria-00544897/
- Séparation de sources dans le cas sous-déterminé : comparaison de deux approches basées sur des décompositions parcimonieuses — XXe colloque GRETSI (traitement du signal et des images), 6-9 septembre 2005, Sep 2005, Louvain-la-Neuve, Belgique. GRETSI, Groupe d'Etudes du Traitement du Signal et des Images, 2005 (Sep 2005) https://hal.inria.fr/inria-00564755/
- Learning unions of orthonormal bases with thresholded singular value decomposition — Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05), IEEE International Conference on Acoustics, Speech, and Signal Processing (May 2005) http://ieeexplore.ieee.org/abstract/document/1416298/
- Learning redundant dictionaries with translation invariance property: the MoTIF algorithm — SPARS'05 - Workshop on Signal Processing with Adaptive Sparse Structured Representations, Inria, 2005, Rennes, France (2005) https://hal.archives-ouvertes.fr/hal-00816804/

## Credentials

- The Joy of React course — Joshua Comeau (Jul 2025) https://courses.joshwcomeau.com/certificate/68702881048493303f074036
- Algorithms on Graphs by University of California San Diego & National Research University Higher School of Economics on Coursera — Coursera (Jan 2020) https://www.coursera.org/account/accomplishments/certificate/ZKJMWYX85H2A
- Data Structures by University of California San Diego & National Research University Higher School of Economics on Coursera — Coursera (Dec 2019) https://www.coursera.org/account/accomplishments/certificate/5HYBM7PRUZ4E
- Algorithmic Toolbox by University of California San Diego & National Research University Higher School of Economics on Coursera — Coursera (Oct 2019) https://www.coursera.org/account/accomplishments/certificate/C2UB3BP2GVME

## Education

- **Université de Rennes** — Doctor of Philosophy - PhD (Jan 2004 - Jan 2007)
  Thesis: Learning structured dictionaries for sparse modeling of multichannel signals  Results: + state of the art on signal representation with a dictionary of atoms + new atomic representation formalism that integrates invariance to phase offset, time translation, filter and pitch shifting + adaptation of the Matching Pursuit decomposition algorithm + machine learning algorithms (K-SVD, MoTIF) for creating the dictionary of atoms + source separation algorithms (Demixing Pursuit, « soft » Demixing Pursuit) + part of the development of Matching Pursuit ToolKit : http://mptk.gforge.inria.fr (C++) + seven conference articles
- **université de metz** — Master (Jan 2002 - Jan 2003)
  \+ thesis: non-standard finite difference models for partial differential equations
- **CentraleSupélec** — Engineer (Jan 2000 - Jan 2003)

## Languages

- French (native)
- Spanish (native)
- English (full professional)

## Links

- GitHub: https://github.com/severo (verified)