factorize: Maximum likelihood factorization

In ccfindR: Cancer Clone Finder

Description

Performs single or multiple rank NMF factorization of count matrix using maximum likelihood

Usage

factorize(object, ranks = 2, nrun = 20, randomize = FALSE,
  nsmpl = 1, verbose = 2, progress.bar = TRUE, Itmax = 10000,
  ncnn.step = 40, criterion = "likelihood", linkage = "average",
  Tol = 1e-05, store.connectivity = FALSE)

Arguments

object	scNMFSet object containing count matrix.
ranks	Rank for factorization; can be a vector of multiple values.
nrun	No. of runs with different initial guess.
randomize	Boolean; if TRUE, input matrix is randomized.
nsmpl	No. of randomized samples to average over.
verbose	The verbosity level: 3, each iteration output printed; 2, each run output printed; 1, each randomized sample output printed; 0, silent.
progress.bar	Display progress bar when nrun > 1 and verbose = 1.
Itmax	Maximum no. of iteration.
ncnn.step	Minimum no. of steps with no change in connectivity matrix to achieve convergence.
criterion	If 'likelihood', iteration stops when fractional changes in likelihood is below tolerance Tol. If criterion = 'connectivity', iteration stops when connectivity matrix does not change for at least ncnn.step steps.
linkage	Method to be sent to hclust in calculating cophenetic correlation.
Tol	Tolerance for checking convergence with criterion = 'likelihood'.
store.connectivity	Returns a list also containing connectivity data.

Details

The main input is the scNMFSet object with count matrix. This function performs non-negative factorization and fills in the empty slots basis, coeff, and ranks.

When run with multiple values of ranks, factorization is repeated for each rank and the slot measure contains quality measures of the ranks. The quality measure likelihood is negative the KL distance of the fit to the target. With nrun > 1, the likelihood is the maximum among all runs.

The quality measure dispersion is the scalar measure of how far the connectivity matrix is from 0, 1. With increasing nrun, dispersion decreases from 1. nrun should be chosen such that dispersion does not change appreciably. With randomization, count matrix of object is shuffled. nsmpl can be used to average over multiple permutations. This averaging applies to each quality measure under a given rank.

Value

Object of class scNMFSet with factorization slots filled.

Examples

set.seed(1)
x <- simulate_data(nfeatures=10,nsamples=c(20,20,60,40,30))
s <- scNMFSet(count=x)
s <- factorize(s,ranks=seq(2,8),nrun=5)
plot(s)

ccfindR documentation built on Nov. 8, 2020, 5:12 p.m.