(posting on-list this time) On Thu, 11 Jul 2024 at 15:18, Popov, Dmitry Yu via Python-list <python-list@python.org> wrote: > > Dear Sirs. > > Does NumPy provide a simple mechanism to identify relatively prime integers, > i.e. integers which don't have a common factor other than +1 or -1? For > example, in case of this array: > [[1,5,8], > [2,4,8], > [3,3,9]] > I can imagine a function which would return array of common factors along > axis 0: [1,2,3]. Those triples of numbers along axis 1 with the factor of1 or > -1 would be relatively prime integers.
It sounds like you want the gcd (greatest common divisor) of each row. The math module can do this: In [1]: a = [[1,5,8], ...: [2,4,8], ...: [3,3,9]] In [2]: import math In [3]: [math.gcd(*row) for row in a] Out[3]: [1, 2, 3] NumPy can also do it apparently: In [10]: np.gcd.reduce(np.transpose(a)) Out[10]: array([1, 2, 3]) https://en.wikipedia.org/wiki/Greatest_common_divisor -- Oscar -- https://mail.python.org/mailman/listinfo/python-list
