I have a list of sets like this:
set_list = [{1, 2, 3}, {4, 5, 1, 6}, {2, 3, 6}, {1, 5, 8}]
Now I want to merge all of the sets together and return a set of all sets like this:
final_set = {1, 2, 3, 4, 5, 6, 8}
I have used this code but it is not working correctly:
tmp_list = []
final_set = set(tmp_list.append(elem) for elem in set_list)
What should I do?
You can use unpacking with set().union for a clean one-liner.
>>> set().union(*set_list)
{1, 2, 3, 4, 5, 6, 8}
You can use reduce function from functools module.
>>> from functools import reduce
>>> set_list = [{1,2,3}, {4,5,1,6}, {2,3,6}, {1,5,8}]
>>> reduce(lambda x, y: x | y, set_list)
{1, 2, 3, 4, 5, 6, 8}
You can iterate over the list and create a union of all sets:
new_set = set()
for i in set_list:
new_set = set.union(new_set, i)
print(new_set)
Output:
{1, 2, 3, 4, 5, 6, 8}
.update without need to assignment, i.e. instead of new_set = set.union(new_set, i) do new_set.update(i)You might do that using comprehension as follows
set_list = [{1, 2, 3}, {4, 5, 1, 6}, {2, 3, 6}, {1, 5, 8}]
final_set = set(elem for sub in set_list for elem in sub)
print(final_set)
output
{1, 2, 3, 4, 5, 6, 8}
Explanation: this is simple adaptation of list-of-lists flattener comprehension which can be used as sets are iterable.
