Random Numbers

How milk handles random numbers

Many algorithms (e.g., kmeans) require random number initialisation.

In milk, all functions that internally use random numbers take an R parameter. If left unspecified (or set to None), then it means that the internal initialisation should be used.

R can be specified by an integer, a random.Random instance, or a numpy.RandomState instance. If the same R is passed twice to the function, then the results are deterministic.

Functions that use random numbers

• kmeans: for initial cluster choice.
• repeated_kmeans: for use in kmeans internally.
• som: for initial choice of points.
• nnmf and sparse_nnmf: for initialisation.

random and numpy.random

There are two randomness mechanisms used internally by milk: random (the standard Python package) and numpy.random. Setting the seed on just one of them will not be enough. You need to set both. This is in alternative to using the R technique outlined above.