xarray.CFTimeIndex.union#

CFTimeIndex.union(other, sort=None)[source]#

Form the union of two Index objects.

If the Index objects are incompatible, both Index objects will be cast to dtype(‘object’) first.

Parameters:

other (Index or array-like) – Index or an array-like object containing elements to form the union with the original Index.
sort (bool or None, default None) – Whether to sort the resulting Index.
- None : Sort the result, except when
  1. self and other are equal.
  2. self or other has length 0.
  3. Some values in self or other cannot be compared. A RuntimeWarning is issued in this case.
- False : do not sort the result.
- True : Sort the result (which may raise TypeError).

Returns:

Index – Returns a new Index object with all unique elements from both the original Index and the other Index.

See also

Index.unique: Return unique values in the index.
Index.intersection: Form the intersection of two Index objects.
Index.difference: Return a new Index with elements of index not in other.

Examples

Union matching dtypes

>>> idx1 = pd.Index([1, 2, 3, 4])
>>> idx2 = pd.Index([3, 4, 5, 6])
>>> idx1.union(idx2)
Index([1, 2, 3, 4, 5, 6], dtype='int64')

Union mismatched dtypes

>>> idx1 = pd.Index(["a", "b", "c", "d"])
>>> idx2 = pd.Index([1, 2, 3, 4])
>>> idx1.union(idx2)
Index(['a', 'b', 'c', 'd', 1, 2, 3, 4], dtype='object')

MultiIndex case

>>> idx1 = pd.MultiIndex.from_arrays(
...     [[1, 1, 2, 2], ["Red", "Blue", "Red", "Blue"]]
... )
>>> idx1
MultiIndex([(1,  'Red'),
    (1, 'Blue'),
    (2,  'Red'),
    (2, 'Blue')],
   )
>>> idx2 = pd.MultiIndex.from_arrays(
...     [[3, 3, 2, 2], ["Red", "Green", "Red", "Green"]]
... )
>>> idx2
MultiIndex([(3,   'Red'),
    (3, 'Green'),
    (2,   'Red'),
    (2, 'Green')],
   )
>>> idx1.union(idx2)
MultiIndex([(1,  'Blue'),
    (1,   'Red'),
    (2,  'Blue'),
    (2, 'Green'),
    (2,   'Red'),
    (3, 'Green'),
    (3,   'Red')],
   )
>>> idx1.union(idx2, sort=False)
MultiIndex([(1,   'Red'),
    (1,  'Blue'),
    (2,   'Red'),
    (2,  'Blue'),
    (3,   'Red'),
    (3, 'Green'),
    (2, 'Green')],
   )