cf.Field.roll

Field.roll(axes, shift, i=False, **kwargs)

Roll the field along a cyclic axis.

A unique axis is selected with the axes and kwargs parameters.

New in version 1.0.

See also

anchor, axis, cyclic, iscyclic, period

Parameters:

axes, kwargs: optional

Select axes. The axes parameter may be one, or a sequence, of:

• None. If no kwargs arguments have been set then all axes are selected. This is the default.

• An integer. Explicitly selects the axis corresponding to the given position in the list of axes of the field’s data array.

  Example:

  To select the third data array axis: axes=2. To select the last axis: axes=-1.

• A slice object. Explicitly selects the axes corresponding to the given positions in the list of axes of the field’s data array.

  Example:

  To select the last three data array axes: axes=slice(-3, None)

• A domain axis identifier. Explicitly selects this axis.

  Example:

  To select axis “dim1”: axes='dim1'.

• Any value accepted by the description parameter of the field’s items method. Used in conjunction with the kwargs parameters to select the axes which span the items that would be identified by this call of the field’s items method: f.items(items=axes, axes=None, **kwargs). See cf.Field.items for details.

  Example:

  To select the axes spanned by one dimensionsal time coordinates: f.roll('T', ndim=1).

If axes is a sequence of any combination of the above then the selected axes are the union of those selected by each element of the sequence. If the sequence is empty then no axes are selected.

shift: int

The number of places by which the selected cyclic axis is to be rolled.

i: bool, optional

If True then update the field in place. By default a new field is created. In either case, a field is returned.

Returns:

out: cf.Field

The rolled field.

Examples: