Hi @alfert,
Can you recommend a way to generate a sublist of N unique elements from a list?
I have a couple of ideas but none seem to be very efficient. For example, to generate 8 unique numbers between 1 and 104:
Solution 1
such_that numbers <- vector(8, integer(1, 104)), when: uniques?(numbers) #define the uniques?/1 helper too
Solution 2
Make a recursive generator that generate a number N0 from 1 to (104 - 8), then generate N1 from (N0 + 1) to (104 - 7), then generate N2 from (N1 + 1) to (104 - 6), etc…
My problem with this one:
- it seems hard to write such a generator
- it is a bit complex
- it skews the generated numbers toward the higher range and is unlikely to be uniform
Solution 3
This is my favorite but I’m not sure how to write it as a generator:
def uniques_numbers() do
1..104
|> Enum.shuffle()
|> Enum.take(8)
end
