datatable.Frame.names¶
The tuple of names of all columns in the frame.
Each name is a non-empty string not containing any ASCII control characters, and jointly the names are unique within the frame.
This property is also assignable: setting DT.names has the effect
of renaming the frame’s columns without changing their order. When
renaming, the length of the new list of names must be the same as the
number of columns in the frame. It is also possible to rename just a
few of the columns by assigning a dictionary {oldname: newname}.
Any column not listed in the dictionary will keep its old name.
When setting new column names, we will verify whether they satisfy the requirements mentioned above. If not, a warning will be emitted and the names will be automatically mangled.
Parameters¶
Tuple[str, ...]When used in getter form, this property returns the names of all
frame’s columns, as a tuple. The length of the tuple is equal to
the number of columns in the frame, ncols.
List[str?] | Tuple[str?, ...] | Dict[str, str?] | NoneThe most common form is to assign the list or tuple of new
column names. The length of the new list must be equal to the
number of columns in the frame. Some (or all) elements in the list
may be None’s, indicating that that column should have
an auto-generated name.
If newnames is a dictionary, then it provides a mapping from
old to new column names. The dictionary may contain less entries
than the number of columns in the frame: the columns not mentioned
in the dictionary will retain their names.
Setting the .names to None is equivalent to using the
del keyword: the names will be set to their default values,
which are usually C0, C1, ....
ValueErrorIf the length of the list/tuple newnames does not match the
number of columns in the frame.
KeyErrorIf newnames is a dictionary containing entries that do not
match any of the existing columns in the frame.
Examples¶
DT = dt.Frame([[1], [2], [3]])
DT.names = ['A', 'B', 'C']
DT.names
('A', 'B', 'C')
DT.names = {'B': 'middle'}
DT.names
('A', 'middle', 'C')
del DT.names
DT.names
('C0', 'C1', 'C2)