data.table: Extension of data.frame for fast indexing, fast ordered joins, fast assignment, fast grouping and list columns

http://datatable.r-forge.r-project.org/



Fast subset, fast grouping, fast assign, fast ordered joins and list columns in a short and flexible syntax, for faster development.

DT[X] is a fast join for large data (DT and X both type data.table).
DT[,sum(b*c),by=a] is fast aggregation (a, b and c are column names).
DT[i,b:=3.14] is fast sub-assignment (to column b) by reference.
DT[,p:=x/sum(x),by=group] to add a new column by reference by group.
fread("big.csv") is 3+ times faster than read.csv(,colClasses,nrow,etc).
10+ times faster than tapply()
100+ times faster than ==
500+ times faster than DF[i,j]<-value
Latest stable release: 1.9.0 on CRAN, 25 Feb 2014

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