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 frame DT;

  • f[2] means “3rd colum” of frame DT;

  • f[int] means “all integer columns” of DT;

  • f[:] means “all columns” of DT not including by() columns, however.

See also

  • g – namespace for joined frames.