MODEL LEARNING PATH
scVI
scVI explains RNA counts using a latent cell state, sequencing depth and a count distribution. An inference network estimates latent variables; a decoder predicts gene-expression parameters for training and posterior analysis.
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A landmark in count-aware variational modeling that separates cell state from library-size and batch effects. Its direct extensions include scANVI, and its probabilistic approach supports successors such as totalVI; this historical lineage, rather than universal benchmark superiority, motivates the featured page.
Chapters
Infer latent variables
Counts enter an encoder that estimates Gaussian cell-state and, in the original model, log-library posteriors.
Distinguish inferred posterior parameters from a sampled cell state.
Predict count distributions
Latent state and batch context determine RNA composition, depth, dispersion and the zero-inflation mixture.
Turn latent context into count means, dispersion and a zero-inflation mixture.
Fit the variational model
The objective combines count reconstruction with cell-state and library-prior KL terms.
Combine reconstruction and prior regularization under a documented reduction.
Analyze the posterior
Posterior draws support predictive moments, expression comparisons and cell-state summaries.
Use posterior draws to summarize uncertainty rather than a single point estimate.
All exercises in this guide
- Affine Projection
- ReLU
- Feedforward Block
- Affine projection and embedding lookup
- Masked Sum
- Masked Mean
- Layer Normalization
- BatchNorm training, evaluation and functional running statistics
- Activations and gated feed-forward transitions
- Gaussian reparameterization, KL, and a minibatch ELBO
- Masked Softmax
- Library-size-scaled rates and batch-specific dispersion
- Stable negative-binomial log probability
- Zero-inflated negative-binomial likelihood
- Posterior predictive moments and total variance
- Posterior differential-expression evidence and expected FDP
- Masked sums, means and weighted reductions