Append columns of one or more
frames to the current Frame.
For example, if the current frame has
n columns, and you are
appending another frame with
k columns, then after this method
succeeds, the current frame will have
n + k columns. Thus, this
method is roughly equivalent to
The frames being cbound must all either have the same number of rows, or some of them may have only a single row. Such single-row frames will be automatically expanded, replicating the value as needed. This makes it easy to create constant columns or to append reduction results (such as min/max/mean/etc) to the current Frame.
If some of the
frames have an incompatible number of rows, then the
operation will fail with an
However, if you set the flag
force to True, then the error will no
longer be raised - instead all frames that are shorter than the others
will be padded with NAs.
If the frames being appended have the same column names as the current frame, then those names will be mangled to ensure that the column names in the current frame remain unique. A warning will also be issued in this case.
Since this method modifies the original Frame in-place, it will have no visible effect when called on a Frame, that is not associated with any variable.
The list/tuple/sequence/generator expression of Frames to append
to the current frame. It may also contain
which will be simply skipped.
True, allows Frames to be appended even if they have unequal
number of rows. The resulting Frame will have number of rows equal
to the largest among all Frames. Those Frames which have less
than the largest number of rows, will be padded with NAs (with the
exception of Frames having just 1 row, which will be replicated
instead of filling with NAs).
This method alters the current frame in-place, and doesn’t return anything.
If trying to cbind frames with the number of rows different from
the current frame’s, and the option
force is not set.
Cbinding frames is a very cheap operation: the columns are copied by
reference, which means the complexity of the operation depends only
on the number of columns, not on the number of rows. Still, if you
are planning to cbind a large number of frames, it will be beneficial
to collect them in a list first and then call a single
instead of cbinding them one-by-one.
It is also possible to cbind frames using the standard
DT[i, j] syntax:
df[:, update(**frame1, **frame2, ...)]
Or, if you need to append just a single column:
df["newcol"] = frame1
dt.cbind()– function for cbinding frames “out-of-place” instead of in-place;
.rbind()– method for row-binding frames.
DT0 = dt.Frame(A=[1, 2, 3], B=[4, 7, 0]) DT1 = dt.Frame(N=[-1, -2, -5]) DT0.cbind(DT1) DT0
At the same time, doing
will have no effect on
DT0[:, :] is a different view frame
that is not assigned to any variable.