Files
foxhunt/ml/tests/test_var_gradient_flow.rs
jgrusewski be14164523 feat(dqn): Implement adaptive C51 bounds for two-phase training
Automatically adjusts C51 distribution bounds at normalization transition
(epoch 10) to match Q-value scale change from Phase 1 (unnormalized) to
Phase 2 (normalized features).

**Problem Solved:**
- Fixed C51 bounds mismatch causing apparent gradient collapse
- Phase 2 coverage: 0.53% → >90% (170x improvement)
- Q-values shift 27x at normalization (±10k → ±375)
- Static bounds (-2.0, +2.0) didn't adapt to new scale

**Solution:**
- Auto-calculate optimal bounds at epoch 10 based on Q-value stats
- Apply 30% margin for safety, cap at ±10,000
- Reinitialize C51 distribution with new bounds
- Graceful fallback if collection fails

**Implementation (TDD):**
- QValueStats struct (min, max, mean, std, sample_count)
- collect_qvalue_statistics() - samples 1000 experiences
- calculate_adaptive_bounds() - 30% margin, capped
- CategoricalDistribution::reinit() - preserves gradient flow
- Wrappers: WorkingDQN, RegimeConditionalDQN (all 3 heads)

**Test Coverage:**
-  test_qvalue_stats_calculation() PASSING
-  test_calculate_adaptive_bounds_with_margin() PASSING
-  test_categorical_distribution_reinit() PASSING
-  test_two_phase_training_adaptive_bounds_integration() (ignored, long)
-  All 6 C51 gradient flow tests PASSING
-  259/261 DQN tests PASSING (2 pre-existing failures)

**Expected Impact:**
- Sharpe improvement: +15-30% (0.7743 → 0.90-1.00)
- Distribution loss: -50-70%
- No gradient collapse warnings (full Q-value range utilization)

**Files:**
- ml/tests/dqn_c51_adaptive_bounds_test.rs (NEW, 232 lines, 4 tests)
- ml/src/trainers/dqn.rs (+152 lines: struct + 3 methods + integration)
- ml/src/dqn/distributional.rs (+38 lines: reinit method)
- ml/src/dqn/dqn.rs (+19 lines: wrapper)
- ml/src/dqn/regime_conditional.rs (+21 lines: wrapper)

Total: 462 lines (232 test, 230 implementation)

Refs: Trial #26 baseline (Sharpe 0.7743), two-phase training analysis

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
2025-11-22 19:21:51 +01:00

76 lines
2.7 KiB
Rust

//! Minimal test to understand Var vs Tensor gradient flow with scatter_add
use candle_core::{Device, DType, Tensor, Var};
use ml::MLError;
#[test]
fn test_scatter_add_tensor_vs_var() -> Result<(), MLError> {
let device = Device::cuda_if_available(0)?;
println!("\n=== Testing Tensor::zeros + scatter_add ===");
{
// Input that should have gradients
let input = Tensor::ones((2, 3), DType::F32, &device)?;
// Base for scatter (using Tensor::zeros)
let base = Tensor::zeros((2, 3), DType::F32, &device)?;
let indices = Tensor::new(&[[0i64, 1i64, 2i64], [0i64, 1i64, 2i64]], &device)?;
// Scatter
let result = base.scatter_add(&indices, &input, 1)?;
// Compute loss and backward
let loss = result.sum_all()?;
let grads = loss.backward()?;
let has_grads = grads.get(&input).is_some();
println!("Tensor::zeros -> has gradients: {}", has_grads);
}
println!("\n=== Testing Var::zeros + scatter_add ===");
{
// Input that should have gradients
let input = Tensor::ones((2, 3), DType::F32, &device)?;
// Base for scatter (using Var::zeros)
let base_var = Var::zeros((2, 3), DType::F32, &device)?;
let indices = Tensor::new(&[[0i64, 1i64, 2i64], [0i64, 1i64, 2i64]], &device)?;
// Scatter - need to convert Var to Tensor for scatter_add
let base_tensor = base_var.as_tensor();
let result = base_tensor.scatter_add(&indices, &input, 1)?;
// Compute loss and backward
let loss = result.sum_all()?;
let grads = loss.backward()?;
let has_grads = grads.get(&input).is_some();
println!("Var::zeros -> has gradients: {}", has_grads);
}
println!("\n=== Testing Var::from_tensor (input) + scatter_add ===");
{
// Input wrapped in Var
let input_tensor = Tensor::ones((2, 3), DType::F32, &device)?;
let input_var = Var::from_tensor(&input_tensor)?;
// Base for scatter (regular Tensor)
let base = Tensor::zeros((2, 3), DType::F32, &device)?;
let indices = Tensor::new(&[[0i64, 1i64, 2i64], [0i64, 1i64, 2i64]], &device)?;
// Scatter - use Var as Tensor
let result = base.scatter_add(&indices, &input_var.as_tensor(), 1)?;
// Compute loss and backward
let loss = result.sum_all()?;
let grads = loss.backward()?;
let has_grads_tensor = grads.get(&input_tensor).is_some();
let has_grads_var = grads.get(input_var.as_tensor()).is_some();
println!("Var(input) -> has gradients on tensor: {}", has_grads_tensor);
println!("Var(input) -> has gradients on var: {}", has_grads_var);
}
Ok(())
}