data.table (version 1.1)

data.table: Enhanced data.frame

Description

Same internal structure as data.frame (i.e. list of vectors) but enhanced extract methods.

Usage

data.table(..., keep.rownames=FALSE, check.names=TRUE, key=NULL)
DT(...)

Arguments

...

Just as ...in data.frame. These arguments are of either the form value or tag = value. Column names are created based on the tag (if present) or the deparsed argument itself. The data.table can

keep.rownames

If ...is a matrix or data.frame, TRUE will retain the rownames of that object into a column 'rn'. If the matrix or data.frame already has a column called 'rn' it will be renamed 'rn.1' via make.names.

check.names

Just as check.names in data.frame(). For example this replaces spaces in column names with period and ensures column names are valid Robject names.

key

Character vector of length 1 containing one or more column names separated by comma which is passed to setkey

Value

• A data.table.

Details

data.table creates a data.table from its arguments just as data.frame does. DT() is an alias for data.table() and is often used instead of as.data.table(). A data.table is a list of vectors, just like a data.frame, however :

See Also

data.frame, tables, setkey

Examples

DF = data.frame(a=1:5, b=letters[1:5])
DT = data.table(a=1:5, b=letters[1:5])
identical(as.data.table(DF), DT)
identical(DT(DF), DT)
identical(dim(DT),dim(DF))
identical(DF$a, DT$a)
DT
tables()
identical(DT(DT,DT), cbind(DT,DT))
DT2=rbind(DT,DT)
DT3 = data.table(A=DT, B=DT, key="A.b")
tables()