data.table

data.table provides a high-performance version of base R’s data.frame with syntax and feature enhancements for ease of use, convenience and programming speed.

The data.table project uses a custom governance agreement and is fiscally sponsored by NumFOCUS. Consider making a tax-deductible donation to help the project pay for developer time, professional services, travel, workshops, and a variety of other needs.

Why `data.table`?

concise syntax: fast to type, fast to read
fast speed
memory efficient
careful API lifecycle management
community
feature rich

Features

fast and friendly delimited file reader: ?fread, see also convenience features for small data
fast and feature rich delimited file writer: ?fwrite
low-level parallelism: many common operations are internally parallelized to use multiple CPU threads
fast and scalable aggregations; e.g. 100GB in RAM (see benchmarks on up to two billion rows)
fast and feature rich joins: ordered joins (e.g. rolling forwards, backwards, nearest and limited staleness), overlapping range joins (similar to IRanges::findOverlaps), non-equi joins (i.e. joins using operators >, >=, <, <=), aggregate on join (by=.EACHI), update on join
fast add/update/delete columns by reference by group using no copies at all
fast and feature rich reshaping data: ?dcast (pivot/wider/spread) and ?melt (unpivot/longer/gather)
any R function from any R package can be used in queries not just the subset of functions made available by a database backend, also columns of type list are supported
has no dependencies at all other than base R itself, for simpler production/maintenance
the R dependency is as old as possible for as long as possible, currently R 3.5.0 (2018), and we continuously test against that version

Installation

install.packages("data.table")

# latest development version (only if newer available)
data.table::update_dev_pkg()

# latest development version (force install)
install.packages("data.table", repos="https://rdatatable.gitlab.io/data.table")

See the Installation wiki for more details.

Usage

Use data.table subset [ operator the same way you would use data.frame one, but…

no need to prefix each column with DT$ (like subset() and with() but built-in)
any R expression using any package is allowed in j argument, not just list of columns
extra argument by to compute j expression by group

library(data.table)
DT = as.data.table(iris)

# FROM[WHERE, SELECT, GROUP BY]
# DT  [i,     j,      by]

DT[Petal.Width > 1.0, mean(Petal.Length), by = Species]
#      Species       V1
#1: versicolor 4.362791
#2:  virginica 5.552000

Getting started

Introduction to data.table vignette
Getting started wiki page
Examples produced by example(data.table)

Cheatsheets

Community

data.table is widely used by the R community. It is being directly used by hundreds of CRAN and Bioconductor packages, and indirectly by thousands. It is one of the top most starred R packages on GitHub, and was highly rated by the Depsy project. If you need help, the data.table community is active on StackOverflow.

A list of packages that significantly support, extend, or make use of data.table can be found in the Seal of Approval document.

Stay up-to-date

click the Watch button at the top and right of GitHub project page
read NEWS file
follow #rdatatable and the r_data_table account on X/Twitter
follow #rdatatable and the r_data_table account on fosstodon
follow the data.table community page on LinkedIn
watch recent Presentations
read recent Articles
read posts on The Raft

Contributing

Guidelines for filing issues / pull requests: Contribution Guidelines.

Citation

Barrett T, Dowle M, Srinivasan A, Gorecki J, Chirico M, Hocking T, Schwendinger B, Krylov I (2026). data.table: Extension of data.frame. R package version 1.18.99, https://r-datatable.com.

@Manual{,
  title = {data.table: Extension of `data.frame`},
  author = {Tyson Barrett and Matt Dowle and Arun Srinivasan and Jan Gorecki and Michael Chirico and Toby Hocking and Benjamin Schwendinger and Ivan Krylov},
  year = {2026},
  note = {R package version 1.18.99},
  url = {https://r-datatable.com},
}