datatable.f¶
The main Namespace
object.
The function of this object is that during the evaluation of a
DT[i,j]
call, the variable f
represents the columns of frame DT
.
Specifically, within expression DT[i, j]
the following
is true:
f.A
means “column A” of frameDT
;f[2]
means “3rd colum” of frameDT
;f[int]
means “all integer columns” ofDT
;f[:]
means “all columns” ofDT
.