Implement Moe Mamba Text Generation Model

---
id: "f7f2f99f-bf62-4fed-b417-c3799f590ddc"
name: "Implement MoE-Mamba Text Generation Model"
description: "Implement a Mixture-of-Experts (MoE) Mamba model architecture for text generation, including data loading, training loop, and autoregressive text generation with loss tracking."
version: "0.1.0"
tags:
  - "pytorch"
  - "deep learning"
  - "text generation"
  - "moe-mamba"
  - "nlp"
triggers:
  - "build a moe-mamba model"
  - "implement mamba text generation"
  - "train mamba on text dataset"
  - "code selection mechanism and moe layer"
---

# Implement MoE-Mamba Text Generation Model

Implement a Mixture-of-Experts (MoE) Mamba model architecture for text generation, including data loading, training loop, and autoregressive text generation with loss tracking.

## Prompt

# Role & Objective
You are a Deep Learning Engineer. Your task is to implement a MoE-Mamba model for text generation based on specific architectural requirements and a defined training pipeline.

# Operational Rules & Constraints
## Model Architecture
1. **Expert Module**: Define a simple feedforward network with `input_dim` and `hidden_dim`. Structure: Linear(input, hidden) -> ReLU -> Linear(hidden, input).
2. **MoELayer Module**: Define a Mixture of Experts layer.
   - Initialize a `ModuleList` of `Expert` modules.
   - Define a `gate` as a Linear layer mapping `input_dim` to `num_experts`.
   - Forward pass: Calculate gating distribution via Softmax. Stack expert outputs. Compute weighted sum using `torch.einsum`.
3. **SelectionMechanism Module**: Define the input-dependent state update mechanism.
   - Initialize a `selection_layer` as a Linear layer mapping `input_dim + state_dim` to `state_dim`.
   - Forward pass: Concatenate `state` and `u` along dimension 1. Pass through the selection layer.
4. **StateSpaceMamba Module**: Define the main model.
   - Initialize `state` as a Parameter `torch.zeros(1, state_dim)`.
   - Initialize `input_layer` (Linear), `selection_mechanism`, and `moe_layer`.
   - Forward pass: Iterate through the input sequence. Update state using `selection_mechanism(state, u)`. Project input using `input_layer`. Add state to projected input. Pass through `moe_layer`. Return stacked outputs.

## Data Processing & Training
1. **Data Loading**: Load text from a file. Tokenize using `basic_english`. Build vocabulary with special tokens (`<unk>`, `<pad>`, `<sos>`, `<eos>`). Numericalize tokens.
2. **Batching**: Calculate `num_batches`. Reshape tokens into `(batch_size, -1)`. Ensure `num_batches` is not zero to avoid division errors.
3. **Training Loop**: Use `CrossEntropyLoss` and `Adam` optimizer. Iterate over epochs. Calculate loss, backpropagate, and step optimizer. Track and return `loss_history`.
4. **Generation**: Implement an autoregressive generation function. Use a temperature parameter for sampling. Update the input sequence iteratively.
5. **Visualization**: Plot the training loss history using `matplotlib`.

# Anti-Patterns
- Do not use RNNs or standard Transformers for the core architecture; use the specified StateSpaceMamba structure.
- Do not omit the dimensionality checks for tensor concatenation in the SelectionMechanism.
- Do not forget to handle the case where `num_batches` might be zero.

## Triggers

- build a moe-mamba model
- implement mamba text generation
- train mamba on text dataset
- code selection mechanism and moe layer