chron, ggplot2 (>= 0.9.0), plyr, reshape, testthat (>= 0.4),
hexbin, fastmatch, nlme

M Dowle, T Short, S Lianoglou with contributions from A Srinivasan, R Saporta
chron, ggplot2 (>= 0.9.0), plyr, reshape, testthat (>= 0.4),
hexbin, fastmatch, nlme, xts, bit64
Enhanced data.frame. Fast indexing, fast ordered joins, fast assignment by reference, fast grouping and list columns in a short and flexible syntax. i and j may be expressions of column names directly, for faster development.  Example: X[Y] is a fast join for large data.

chron, ggplot2 (>= 0.9.0), plyr, reshape, testthat (>= 0.4),
hexbin, fastmatch, nlme, xts

M Dowle, T Short, S Lianoglou, A Srinivasan with contributions from R Saporta, E Antonyan
Fast aggregation of large data (e.g. 100GB in RAM), fast ordered joins, fast add/modify/delete of columns by group using no copies at all, list columns and a fast file reader (fread). Offers a natural and flexible syntax, for faster development.

ggplot2 (>= 0.9.0), plyr, reshape, testthat (>= 0.4), hexbin,
fastmatch, nlme, xts, bit64

M Dowle, A Srinivasan, T Short, S Lianoglou with contributions from R Saporta, E Antonyan
ggplot2 (>= 0.9.0), plyr, reshape, reshape2, testthat (>=
0.4), hexbin, fastmatch, nlme, xts, bit64, gdata,
GenomicRanges, caret, knitr, curl, zoo, plm

Create tree structures from hierarchical data, and use the utility
methods to traverse the tree in various orders. Aggregate, print, convert to and from data.frame,
and apply functions to your tree data. Useful for decision trees, machine learning, finance, and
many other applications.

General Purpose Hierarchical Data Structure
testthat, knitr, ape, networkD3, yaml, jsonlite, DiagrammeR,
igraph, treemap, curl, doParallel, foreach, htmlwidgets
Create tree structures from hierarchical data, and use the utility
methods to traverse the tree in various orders. Aggregate, cumulate, print, convert to and from data.frame,
and apply functions to your tree data. Useful for decision trees, machine learning, finance, conversion
from and to JSON, and many other applications.