### Navigation

- index
- modules |
- next |
- previous |
- NumPy v1.3 Manual (DRAFT) »
- NumPy Reference »
- Routines »
- Set routines »

# numpy.unique1d

`numpy.``unique1d`(ar1, return_index=False, return_inverse=False)

  Find the unique elements of an array.

  Parameters: | ar1 : array_like This array will be flattened if it is not already 1-D. return_index : bool, optional If True, also return the indices against ar1 that result in the unique array. return_inverse : bool, optional If True, also return the indices against the unique array that result in ar1.
  Returns: | unique : ndarray The unique values. unique_indices : ndarray, optional The indices of the unique values. Only provided if return_index is True. unique_inverse : ndarray, optional The indices to reconstruct the original array. Only provided if return_inverse is True.

  See also

  `numpy.lib.arraysetops`
    Module with a number of other functions for performing set operations on arrays.

  Examples

      >>> np.unique1d([1, 1, 2, 2, 3, 3])
      array([1, 2, 3])
      >>> a = np.array([[1, 1], [2, 3]])
      >>> np.unique1d(a)
      array([1, 2, 3])

  Reconstruct the input from unique values:

      >>> np.unique1d([1,2,6,4,2,3,2], return_index=True)
      >>> x = [1,2,6,4,2,3,2]
      >>> u, i = np.unique1d(x, return_inverse=True)
      >>> u
      array([1, 2, 3, 4, 6])
      >>> i
      array([0, 1, 4, 3, 1, 2, 1])
      >>> [u[p] for p in i]
      [1, 2, 6, 4, 2, 3, 2]

### Navigation

- index
- modules |
- next |
- previous |
- NumPy v1.3 Manual (DRAFT) »
- NumPy Reference »
- Routines »
- Set routines »