The unique elements of the array.
Returns a new object with the sorted unique elements in a one dimensional array.
| Examples: |
|---|
>>> d = cf.Data([[4, 2, 1], [1, 2, 3]], 'metre')
>>> d.unique
<CF Data: [1, 2, 3, 4] metre>
>>> d[1, -1] = cf.masked
>>> d.unique
<CF Data: [1, 2, 4] metre>