by Matt Dowle

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Extension of Data.frame

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.


Functions in data.table

Name Description
IDateTime Integer based date class
copy Copy an entire object
data.table-package Enhanced data.frame
chmatch Faster match of character vectors
rleid Generate run-length type group id Efficient data.table to xts conversion
rbindlist Makes one data.table from a list of many
last Last item of an object
tables Display all objects of class 'data.table'
setattr Set attributes of objects by reference
fread Fast and friendly file finagler
shift Fast lead/lag for vectors and lists
truelength Over-allocation access
like Convenience function for calling regexpr.
patterns Regex patterns to extract columns from data.table Efficient xts to conversion
tstrsplit strsplit and transpose the resulting list efficiently
address Address in RAM of a variable
timetaken Pretty print of time taken
transpose Efficient transpose of list
:= Assignment by reference Data table utilities
setcolorder Fast column reordering of a data.table by reference Subsetting data.tables
J Creates a Join data table
all.equal Equality Test Between Two Data Tables Remove rows with missing values on columns specified
duplicated Determine Duplicate Rows Runs a set of tests.
foverlaps Fast overlap joins
data.table-class S4 Definition for data.table
setNumericRounding Change or turn off numeric rounding Fast dcast for data.table
frank Fast rank
between Convenience function for range subset logic.
setkey Create key on a data table
setDF Convert a data.table to data.frame by reference
setDT Convert lists and data.frames to data.table by reference Fast melt for data.table
setorder Fast row reordering of a data.table by reference
merge Merge Two Data Tables
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