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Detailed explanation of the use of the union function
union() can "merge" collections
grammar
set.union( set )
parameter
- set : (required) the set to be merged
return value
- Return a new merged collection
Example: Merge two collections
set1 = {
1, 2, 3}
set2 = {
4, 5, 6}
new_set = set1.union(set2)
print(new_set)
output:
{
1, 2, 3, 4, 5, 6}
From the pseudo-source code (Python built-in functions cannot see the source code, only the function description is provided), we can see that union() can return the union of multiple sets as a new set.
1. Merge multiple collections
union() can receive multiple parameters, which means that we can merge "multiple collections" at the same time .
set1 = {
1, 2, 3}
set2 = {
4, 5, 6}
set3 = {
7, 8, 9}
new_set = set1.union(set2, set3)
print(new_set)
output:
{
1, 2, 3, 4, 5, 6, 7, 8, 9}
2. Combine other types
The parameter received by union() is an iterable type ( iterable ), which means that we can combine collections with other iterable types.
2.1. Merge strings
"String" is an iterable type that can be merged with a collection.
set1 = {
1, 2, 3}
new_set = set1.union('abc')
print(new_set)
output:
{
1, 2, 3, 'a', 'c', 'b'}
2.2. Merge list
"Lists" are also iterable types that can be merged with collections.
set1 = {
1, 2, 3}
list1 = [4, 5, 6]
new_set = set1.union(list1)
print(new_set)
output:
{
1, 2, 3, 4, 5, 6}
2.3. Merge tuples
"Tuples" are also iterable types that can be merged with collections.
set1 = {
1, 2, 3}
tuple1 = (4, 5, 6)
new_set = set1.union(tuple1)
print(new_set)
output:
{
1, 2, 3, 4, 5, 6}
2.4. Merge dictionaries
"Dictionary" is also an iterable type that can be merged with collections; unlike other types, dictionaries only merge keys, not values.
set1 = {
1, 2, 3}
dict1 = {
'key1': 1, 'key2': 2}
new_set = set1.union(dict1)
print(new_set)
output:
{
1, 2, 3, 'key1', 'key2'}
2.5, merge bytes type
"bytes" is also an iterable type, which can be merged with a collection; but bytes is a byte stream, and characters will be converted and then merged.
set1 = {
1, 2, 3}
bytes1 = b'abc'
new_set = set1.union(bytes1)
print(new_set)
output:
{
1, 2, 3, 97, 98, 99}
2.6. Values cannot be merged
"Value" is not iterable and cannot be merged with a collection, otherwise an error will be reported TypeError: 'int' object is not iterable
set1 = {
1, 2, 3}
new_set = set1.union(11)
output:
