Union of Sets in Python

The update method allows not only to add elements, but also to combine several sets.

Let us have two sets:

pythonst1 = {'a', 'b', 'c', 'd'}
st2 = {1, 2, 3, 4}

Let's add the second set to the first:

pythonst1.update(st2)

And then we output the first set to the console:

pythonprint(st1) # {'c', 1, 2, 3, 4, 'b', 'd', 'a'}

You can also pass multiple sets to the update method. Let's create a third set:

pythonst3 = {'x', 'y', 'z'}

Now let's add the second and third sets to the first:

pythonst1.update(st2, st3)

Let's output the first set to the console:

pythonprint(st1) # {1, 2, 3, 4, 'd', 'y', 'x', 'c', 'a', 'b', 'z'}

The union of sets can be written in a more concise form using the operator |. Let's rewrite the previous example in a concise form:

pythonst1 = st2 | st3

pythonst1 = {'a', 'b', 'c', 'd', 'e'}
st2 = {'d', 'e', 'f', 'g', 'h'}

pythonst1 = {'2', '4', '6'}
st2 = {7, 8, 9}
st3 = {'1', '3', '4'}

pythonst1 = {1, 2, 3}
st2 = {'a', 'b', 'c'}
st3 = {4, 5, 6}
st4 = {'d', 'e', 'f'}