What is a pythonic way of slicing a set?

Question

I have some list of data, for example:

some_data = [1, 2, 4, 1, 6, 23, 3, 56, 6, 2, 3, 5, 6, 32, 2, 12, 5, 3, 2]

and I want to get unique values with fixed length (I don't care which I will get) and I also want it to be a set.

I know that I can do set from some_data then make it list, crop it and then make it set again.

set(list(set(some_data))[:5])  # doesn't look so friendly

I understand that I don't have __getitem__ method in set which wouldn't make the whole slice thing possible, but if there is a chance to make it look better?

And I completely understand that set is unordered. So it doesn't matter which elements are in final set.

Possible options are to use:

• ordered-set

• using dict with None values:

   set(dict(map(lambda x: (x, None), some_data)).keys()[:2])  # not that great
  

Answer 1

You could sample the set

import random
set(random.sample(my_set, 5)) 

The advantage of this you'll get different numbers each time

Answer 2

You could try a simple set comprehension:

some_data = [1, 2, 4, 1, 6, 23, 3, 56, 6, 2, 3, 5, 6, 32, 2, 12, 5, 3, 2]
n = {x for i, x in enumerate(set(some_data)) if i < 5}
print n

Output:

set([32, 1, 2, 3, 4])

Answer 3

I went through all the examples above and all of the answers are indeed great. I have one more approach to share in order to slice sets i.e. the use of the * operator. This approach requires us to use variables in order to store the memory address/references of elements. The final output we get after slicing is a list so if we want the final output to be a set we need to typecast the final result into a list or any other datatype we want to. The image of the code cannot be embedded since I do not have 10 points and therefore a link to the image of the code is given. Kindly do have a look and feel free to provide any suggestions regarding the same. Thanks.

The sample code image