Jeroen Janssens
Head of Developer Relations
Jeroen Janssens, PhD, is Head of Developer Relations at Posit, PBC. His expertise lies in visualizing data, implementing machine learning models, and building solutions using Python, R, JavaScript, and Bash. He’s passionate about open source and sharing knowledge. He’s the author of Python Polars: The Definitive Guide (O’Reilly, 2025) and Data Science at the Command Line (O’Reilly, 2021). Jeroen holds a PhD in machine learning from Tilburg University and an MSc in artificial intelligence from Maastricht University. He lives with his wife and two kids in Rotterdam, the Netherlands.
Software by Jeroen Janssens
devtools
Tools to make an R developer's life easier
dplyr
dplyr: A grammar of data manipulation
forcats
🐈🐈🐈🐈: tools for working with categorical variables (factors)
ggplot2
An implementation of the Grammar of Graphics in R
haven
Read SPSS, Stata and SAS files from R
lubridate
Make working with dates in R just that little bit easier
plotnine
A Grammar of Graphics for Python
purrr
A functional programming toolkit for R
readr
Read flat files (csv, tsv, fwf) into R
stringr
A fresh approach to string manipulation in R
tidyr
Tidy Messy Data
usethis
Set up commonly used 📦 components
archive
R bindings to libarchive, supporting a large variety of archive formats
asciicast
Turn R scripts into terminal screencasts
available
Check if a package name is available to use
bench
High Precision Timing of R Expressions
bigrquery
An interface to Google's BigQuery from R
bit64
An R package with an S3 Class for Vectors of 64bit Integers
blob
A simple S3 class for representing BLOBs
bonsai
parsnip wrappers for tree-based models
brio
Basic R Input Output
broom
Convert statistical analysis objects from R into tidy format
brulee
High-Level Modeling Functions with 'torch'
butcher
Reduce the size of model objects saved to disk
cachem
Key-value caches for R
callr
Call R from R
censored
Parsnip wrappers for survival models
chatlas
Your friendly guide to building LLM chat apps in Python with less effort and more clarity
cli
Tools for making beautiful & useful command line interfaces
clock
A Date-Time Library for R
concept-maps
Concept maps for all things data science
coro
Coroutines for R
crayon
🖍️ R package for colored terminal output — now superseded by cli
DBI
A database interface (DBI) definition for communication between R and RDBMSs
dbplyr
Database (DBI) backend for dplyr
debugme
Easy and efficient debugging for R packages
desc
Manipulate DESCRIPTION files
dials
Tools for creating tuning parameter values
discrim
Wrappers for discriminant analysis and naive Bayes models for use with the parsnip package
downlit
Syntax Highlighting and Automatic Linking
dtplyr
Data table backend for dplyr
duckplyr
A drop-in replacement for dplyr, powered by DuckDB for speed
ellmer
Call LLM APIs from R
embed
Extra recipes for predictor embeddings
filelock
Cross platform file locking in R
finetune
Additional functions for model tuning
fs
Provide cross platform file operations based on libuv
gargle
Infrastructure for calling Google APIs from R, including auth
gh
Minimalistic GitHub API client in R
glue
Glue strings to data in R. Small, fast, dependency free interpreted string literals
gmailr
Access the Gmail RESTful API from R
hardhat
Construct Modeling Packages
httr2
Make HTTP requests and process their responses. A modern reimagining of httr
infer
An R package for tidyverse-friendly statistical inference
isoband
isoband: An R package to generate contour lines and polygons
keyring
:closed_lock_with_key: Access the system credential store from R
later
Schedule an R function or formula to run after a specified period of time
lifecycle
Manage the life cycle of your exported functions and arguments
lobstr
Understanding complex R objects with tools similar to str()
magrittr
Improve the readability of R code with the pipe
mirai
Minimalist Async Evaluation Framework for R
multilevelmod
Parsnip wrappers for mixed-level and hierarchical models
nanonext
R binding for NNG (Nanomsg Next Gen)
nanoparquet
R package to read and write Parquet files
odbc
Connect to ODBC databases (using the DBI interface)
pak
A fresh approach to package installation
parsnip
A tidy unified interface to models
pingr
ICMP and TCP ping and related tools
pkgbuild
Find tools needed to build R packages
pkgdepends
R Package Dependency Resolution
pkgdown
Generate static html documentation for an R package
pkgload
Simulate installing and loading a package
prettycode
Syntax highlight R code in the terminal
prettyunits
Pretty, human readable formatting of quantities
probably
Tools for post-processing class probability estimates
processx
Execute and Control Subprocesses from R
profvis
Visualize R profiling data
progress
Progress bar in your R terminal
ps
R package to query, list, manipulate system processes
R6
Encapsulated object-oriented programming for R
ragnar
RAG in R
rappdirs
Find OS-specific directories to store data, caches, and logs. A port of python's AppDirs
rcmdcheck
Run R CMD check from R and collect the results
remotes
Install R packages from GitHub, GitLab, Bitbucket, git, svn repositories, URLs
reprex
Render bits of R code for sharing, e.g., on GitHub or StackOverflow
rlang
Low-level API for programming with R
rsample
Classes and functions to create and summarize resampling objects
rules
parsnip extension for rule-based models
sessioninfo
Print Session Information
slider
Sliding Window Functions
supported-by-posit
Add a "Supported by Posit" badge to a package website
testthat
An R 📦 to make testing 😀
tibble
A modern re-imagining of the data frame
tidymodels
Easily install and load the tidymodels packages
tidypredict
Run predictions inside the database
tidyselect
A backend for functions taking tidyverse selections
tune
Tools for tidy parameter tuning
urlchecker
Run CRAN URL checks from older versions of R
usemodels
Boilerplate Code for tidymodels
vctrs
Generic programming with typed R vectors
vdiffr
Visual regression testing and graphical diffing with testthat
vitals
Large language model evaluation for R
vroom
Fast reading of delimited files
watcher
Watch the File System for Changes
webfakes
Fake web apps for HTTP testing R packages
withr
Methods For Temporarily Modifying Global State
workflows
Modeling Workflows
workflowsets
Create a collection of modeling workflows
xml2
Bindings to libxml2
xopen
Open System Files, URLs, Anything
yardstick
Tidy methods for measuring model performance
zip
Platform independent zip compression via miniz
Posts and resources by Jeroen Janssens
