Example callbacks (stnmf.callbacks)

Exemplary callbacks illustrating their use with stnmf.STNMF.

consensus(self, i, itor, callback_data, ...)	Callback function to run consensus analysis
perturbation(self, i, itor, callback_data[, ...])	Callback function to apply different perturbations to the modules at certain intervals
residual(self, i, itor, callback_data[, ...])	Callback function to view and record the course of the reconstruction residual
stopping_criterion(self, i, itor, callback_data)	Callback function to implement a custom stopping criterion based on relative reconstruction improvement

Detail

Callbacks allow to safely modify the algorithm of subunit decomposition in many aspects without having to dive deep into the NMF code. The user can specify a function that will be called at each loop iteration in the iterative process of NMF. Code execution jumps out of the internal code into the user function and returns afterwards to continue until the next iteration. The function defined by the user will be supplied with and has access to the current (mutable) state of the decomposition at each iteration.

Among many other things, this allows…

• to record the course of certain properties throughout the iterative process,

• to have the process be interrupted prematurely based on termination criteria,

• to change properties of the current decomposition to modify the course of the decomposition,

• and to leverage parts of the algorithm to completely redefine how subunits are decomposed.

A callback function can be understood as a plug-in or add-on extension of the internal code.