# cf.DimensionCoordinate.period

`DimensionCoordinate.``period`(*value)

  Set the period for cyclic coordinates.

  Parameters: | value: data-like or `None`, optional The period. The absolute value is used. A data-like scalar object is any object containing scalar data which could be used to create a `cf.Data` object. Example: Instances, `x`, of following types are all examples of scalar data-like objects (because `cf.Data(x)` creates a valid `cf.Data` object): `int`, `float`, `str`, and scalar-valued `numpy.ndarray`, `cf.Data`, `cf.Coordinate`, `cf.Field`.
  Returns: | out: `cf.Data` or `None` The period prior to the change, or the current period if no value was specified. In either case, None is returned if the period had not been set previously.
  Examples: |

      >>> print c.period()
      None
      >>> c.Units
      <CF Units: degrees_east>
      >>> print c.period(360)
      None
      >>> c.period()
      <CF Data: 360.0 'degrees_east'>
      >>> import math
      >>> c.period(cf.Data(2*math.pi, 'radians'))
      <CF Data: 360.0 degrees_east>
      >>> c.period()
      <CF Data: 6.28318530718 radians>
      >>> c.period(None)
      <CF Data: 6.28318530718 radians>
      >>> print c.period()
      None
      >>> print c.period(-360)
      None
      >>> c.period()
      <CF Data: 360.0 degrees_east>