Make a copy of the frame.
The returned frame will be an identical copy of the original, including column names, types, and keys.
By default, copying is shallow with copy-on-write semantics. This means that only the minimal information about the frame is copied, while all the internal data buffers are shared between the copies. Nevertheless, due to the copy-on-write semantics, any changes made to one of the frames will not propagate to the other; instead, the data will be copied whenever the user attempts to modify it.
It is also possible to explicitly request a deep copy of the frame
by setting the parameter
True. With this flag, the
returned copy will be truly independent from the original. The
returned frame will also be fully materialized in this case.
Flag indicating whether to return a “shallow” (default), or a “deep” copy of the original frame.
A new Frame, which is the copy of the current frame.
DT1 = dt.Frame(range(5)) DT2 = DT1.copy() DT2[0, 0] = -1 DT2
Non-deep frame copy is a very low-cost operation: its speed depends on the number of columns only, not on the number of rows. On a regular laptop copying a 100-column frame takes about 30-50µs.
Deep copying is more expensive, since the data has to be physically written to new memory, and if the source columns are virtual, then they need to be computed too.
Another way to create a copy of the frame is using a
DT[i, j]expression (however, this will not copy the key property):
Frameclass also supports copying via the standard Python library
import copy DT_shallow_copy = copy.copy(DT) DT_deep_copy = copy.deepcopy(DT)