Question

I am trying to create a set that contains all the results as returned by a function which is applied to each element in a set. The following code snippet hopefully clarifies:

results = set()    
for node in nodes:
    results = set.union(results, foo(node))

Although the code accomplishes what I want, I am sure it can be rewritten much better and more concise. As I have to repeat this construct several times, any help is much appreciated.

Thanks in advance.

Answer 1

results = set()    
for node in nodes:
    results.update(foo(node))

or

results = set.union(*[foo(node) for node in nodes])

If nodes can be empty, then use this to make sure it doesn’t throw an exception:

results = set.union(set(), *[foo(node) for node in nodes])