pandas.Index.union#
- final Index.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.
Changed in version 0.25.0.
- Parameters
- otherIndex or array-like
- sortbool or None, default None
Whether to sort the resulting Index.
None : Sort the result, except when
self and other are equal.
self or other has length 0.
Some values in self or other cannot be compared. A RuntimeWarning is issued in this case.
False : do not sort the result.
- Returns
- unionIndex
Examples
Union matching dtypes
>>> idx1 = pd.Index([1, 2, 3, 4]) >>> idx2 = pd.Index([3, 4, 5, 6]) >>> idx1.union(idx2) Int64Index([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')], )