# Constants of the `cf` module

`cf.``masked`

  The `cf.masked` constant allows data array values to be masked by direct assignment. This is consistent with the behaviour of numpy masked arrays.

  For example, masking every element of a field’s data array could be done as follows:

      >>> f[...] = cf.masked

  To mask every element of a field’s data array whose value is less than zero:

      >>> f.where(cf.lt(0), cf.masked, i=True)

  See also

  cf.Field.hardmask, cf.Field.subspace, cf.Field.where, cf.lt