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fastTopics (version 0.6-192)

simulate_count_data: Simulate Count Data from Poisson NMF Model

Description

Simulate a counts matrix X such that X[i,j] is Poisson with rate (mean) Y[i,j], where Y = tcrossprod(L,F), L is an n x k loadings (“activations”) matrix, and F is an m x k factors (“basis vectors”) matrix. The entries of matrix L are drawn uniformly at random between zero and lmax, and the entries of matrix F are drawn uniformly at random between 0 and fmax.

Usage

simulate_count_data(n, m, k, fmax = 1, lmax = 1, sparse = FALSE)

Value

The return value is a list containing the counts matrix

X and the factorization, F and L, used to generate the counts.

Arguments

n

Number of rows in simulated count matrix. The number of rows should be at least 2.

m

Number of columns in simulated count matrix. The number of columns should be at least 2.

k

Number of factors, or “topics”, used to determine Poisson rates. The number of topics should be 1 or more.

fmax

Factors are drawn uniformly at random between zero and fmax.

lmax

Loadings are drawn uniformly at random between zero and lmax.

sparse

If sparse = TRUE, convert the counts matrix to a sparse matrix in compressed, column-oriented format; see sparseMatrix.

Details

Note that only minimal argument checking is performed. This function is mainly used to simulate small data sets for the examples and package tests.