# 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¶

return
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.

new_names
List[str?] | Tuple[str?, ...] | Dict[str, str?] | None

The 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 new_names 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, ....

except
ValueError | KeyError
 dt.exceptions.ValueError raised If the length of the list/tuple new_names does not match the number of columns in the frame. dt.exceptions.KeyError raised If new_names 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)