ID : 479

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Tags : PythonPython Set

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In this tutorial, we will introduce different methods to join two .

`A |= B`

`A.update(B)`

`A.union(B)`

`reduce(operator.or_, [A, B])`

`A |= B`

to Join Two Sets in Python`A |= B`

adds all elements of set `B`

to set `A`

.

`>>> A = {4, 5, 6, 7} >>> B = {6, 7, 8, 9} >>> A |= B >>> A {4, 5, 6, 7, 8, 9} `

`A.update(B)`

to Join Two Sets in Python`A.update(B)`

method is identical to `A |= B`

. It modifes set `A`

in place.

`>>> A = ["a", "b", "c"] >>> B = ["b", "c", "d"] >>> A.update(B) >>> A ["a", "b", "c", "d"] `

`A.union(B)`

to Join Two Sets in Python`A.union(B)`

returns the union of sets `A`

and `B`

. It doesnâ€™t modify set `A`

in place but returns a new set.

`>>> A = {4, 5, 6, 7} >>> B = {6, 7, 8, 9} >>> A.union(B) {1, 2, 3, 4, 5, 6} >>> A {1, 2, 3, 4} `

It is identical to `A | B`

.

`reduce(operator.or_, [A, B])`

to Join Two Sets in Python`operator.or_(A, B)`

returns the bitwiser `or`

of `A`

and `B`

, or union of sets `A`

and `B`

if `A`

and `B`

are sets.

`reduce`

in Python 2.x or `functools.reduce`

in both Python 2.x and 3.x applies function to the items of iterable.

Therefore, `reduce(operator.or_, [A, B])`

applies `or`

function to `A`

and `B`

. It is the identical to the Python expression `A | B`

`>>> import operator >>> from functools import reduce >>> A = {4, 5, 6, 7} >>> B = {6, 7, 8, 9} >>> reduce(operator.or_, [A, B]) {4, 5, 6, 7, 8, 9} `

Attention

`reduce`

is the built-in function in Python 2.x, but is deprecated in Python 3.

Therefore, we need to use `functools.reduce`

to make the codes compatible in Python 2 and 3.