union(self, other, sort=None)

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

versionchanged

Parameters

other : Index or array-like

sort : bool or None, default None

Whether to sort the resulting Index.

• None

  None

Returns

union : Index

Form the union of two Index objects.

Examples

Union matching dtypes

This example is valid syntax, but we were not able to check execution

>>> 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

This example is valid syntax, but we were not able to check execution

>>> 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

This example is valid syntax, but we were not able to check execution

>>> idx1 = pd.MultiIndex.from_arrays(
...     [[1, 1, 2, 2], ["Red", "Blue", "Red", "Blue"]]
... )
... idx1
MultiIndex([(1,  'Red'),
    (1, 'Blue'),
    (2,  'Red'),
    (2, 'Blue')],
   )

This example is valid syntax, but we were not able to check execution

>>> idx2 = pd.MultiIndex.from_arrays(
...     [[3, 3, 2, 2], ["Red", "Green", "Red", "Green"]]
... )
... idx2
MultiIndex([(3,   'Red'),
    (3, 'Green'),
    (2,   'Red'),
    (2, 'Green')],
   )

This example is valid syntax, but we were not able to check execution

>>> idx1.union(idx2)
MultiIndex([(1,  'Blue'),
    (1,   'Red'),
    (2,  'Blue'),
    (2, 'Green'),
    (2,   'Red'),
    (3, 'Green'),
    (3,   'Red')],
   )

This example is valid syntax, but we were not able to check execution

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

See :

Local connectivity graph

Hover to see nodes names; edges to Self not shown, Caped at 50 nodes.

Using a canvas is more power efficient and can get hundred of nodes ; but does not allow hyperlinks; , arrows or text (beyond on hover)

SVG is more flexible but power hungry; and does not scale well to 50 + nodes.

All aboves nodes referred to, (or are referred from) current nodes; Edges from Self to other have been omitted (or all nodes would be connected to the central node "self" which is not useful). Nodes are colored by the library they belong to, and scaled with the number of references pointing them

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File: /pandas/core/indexes/base.py#3058
type: <class 'function'>
Commit: