pandas.Index.union#

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

Form the union of two Index objects.

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

Parameters:

otherIndex or array-like

sortbool or None, default None

Whether to sort the resulting Index.

• None : Sort the result, except when

  1. self andother are equal.

  2. self orother has length 0.

  3. Some values inself orother 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

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"]]...)>>>idx1MultiIndex([(1,  'Red'),    (1, 'Blue'),    (2,  'Red'),    (2, 'Blue')],   )>>>idx2=pd.MultiIndex.from_arrays(...[[3,3,2,2],["Red","Green","Red","Green"]]...)>>>idx2MultiIndex([(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')],   )