MoM: Mixture of Multinomial Model Prior description class
Description
An S4 class to represent a Mixture of Multinomial model.
Such model can be used to cluster a data matrix \(X\) with the following generative model :
$$ \pi \sim Dirichlet(\alpha)$$
$$ Z_i \sim \mathcal{M}(1,\pi)$$
$$ \theta_{k} \sim Dirichlet(\beta)$$
$$ X_{i.}|Z_{ik}=1 \sim \mathcal{M}(L_i,\theta_{k})$$
With \(L_i=\sum_d=1^DX_{id}\). These classes mainly store the prior parameters value (\(\alpha,\beta\)) of this generative model.
The MoM-class must be used when fitting a simple Mixture of Multinomials whereas the MoMPrior-class must be sued when fitting a CombinedModels-class.
Usage
MoMPrior(beta = 1)
MoM(alpha = 1, beta = 1)
Value
a MoMPrior-class object
a MoM-class object
Arguments
beta
Dirichlet over vocabulary prior parameter (default to 1)
alpha
Dirichlet prior parameter over the cluster proportions (default to 1)