python - Generate a large list of points with no duplicates

Question

I want to create a large list containing 20,000 points in the form of:

[[x, y], [x, y], [x, y]]

where x and y can be any random integer between 0 and 1000. How would I be able to do this such that there are no duplicate coordinates [x, y]?

Answer 1

You could just use a while loop to pad it out until it's big enough:

>>> from random import randint
>>> n, N = 1000, 20000
>>> points = {(randint(0, n), randint(0, n)) for i in xrange(N)}
>>> while len(points) < N:
...     points |= {(randint(0, n), randint(0, n))}
...     
>>> points = list(list(x) for x in points)

Your initial idea was probably slow because it was iterating lists for checking containmentship, which is O(n). This uses sets which are faster, and then only converts to the list structure once at the end.