python-math #6: feat(math): PCA warm start in clojure-legacy engine mode (PR-B) - #2640
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Pull request overview
Adds Clojure-parity PCA warm-start behavior to the Python Delphi math pipeline when POLISMATH_ENGINE_MODE=clojure-legacy, by threading the previous tick’s PCA components into the power-iteration solver as start vectors, while keeping the default improved mode cold/recompute behavior unchanged.
Changes:
- Extend
pca_project_dataframeto acceptstart_vectorsandrequire_powerit, and ensure sklearn PCA is not used when warm-start/powerit is required (warn + fall back). - In
Conversation._compute_pca, when in legacy mode, require power-iteration and feed previous tick’spca['comps']as warm-start vectors when available. - Add a dedicated test module covering threading, fallback warning, and two-tick warm-start behavior.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
delphi/polismath/pca_kmeans_rep/pca.py |
Adds warm-start/powerit forcing controls and sklearn-conflict warning/fallback; threads start_vectors into powerit_pca. |
delphi/polismath/conversation/conversation.py |
Wires legacy engine mode to require power-iteration and optionally seed PCA from previous tick comps. |
delphi/tests/test_pca_warm_start.py |
New tests validating warm-start threading, warning/fallback behavior, and cold-path invariance across modes. |
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python-math #43: docs(delphi): s7 goal state + journal — mode collapse executed, battery 20/20
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…ode (PR-B) ## What When `POLISMATH_ENGINE_MODE=clojure-legacy` (the engine setting that reproduces the old Clojure engine's behavior exactly), the previous tick's unit PCA components are threaded into the power-iteration PCA as start vectors, matching Clojure (`conversation.clj:381-387` passes `:start-vectors (get-in conv [:pca :comps])` into `powerit-pca`, `pca.clj:86-105`; new columns are absorbed by 1-padding, `pca.clj:46-49`). Default `improved` mode is unchanged (cold recompute). ## Changes - `pca_project_dataframe` gains `start_vectors` (default `None`) and `require_powerit` (default `False`). With both absent, the code path is BYTE-IDENTICAL to before. When a warm start is supplied — or required by legacy mode — and `POLISMATH_PCA_IMPL=sklearn` is set, we warn and fall back to power iteration: sklearn's SVD has no start-vector hook, so running it would silently drop the warm start (documented at the guard). - `powerit_pca` already supported `start_vectors` + 1-padding + all-zero -> `None`; this just wires the production callers to it. - `Conversation._compute_pca`: in legacy mode sets `require_powerit=True` and, when `prev_pca` has real components, `start_vectors` = the previous components (empty/cold -> `None`, which yields the deterministic random cold draw). `prev_pca` is captured in `recompute()` (PR-A, the previous commit in this series). ## Semantic judgment calls (integrator, please verify vs Clojure) - The warm start is POSITIONAL: previous components align to current columns by index, and new (appended) comments are 1-padded — exactly Clojure's behavior. Column removal/reorder would misalign, but Clojure is append-only here, and `_power_iteration` truncates a too-long start vector defensively (pre-existing, `pca.py:124-127`) where Clojure would error. - "Legacy implies powerit" is enforced via `require_powerit=True` even on the cold first tick, so an operator setting `PCA_IMPL=sklearn` + legacy still gets power iteration (with a warning). ## Testing TDD RED evidence (before implementing): `test_start_vectors_reach_powerit` — "TypeError: pca_project_dataframe() got an unexpected keyword argument 'start_vectors'"; `test_legacy_tick2_receives_tick1_comps` — "assert None is not None" (tick 2 ran cold; no components threaded). Tests: 8 new (start_vectors threading, sklearn-conflict warning, improved-mode byte-identity, two-tick legacy warm start via spy, angle stability, cold-tick cross-mode identity). Full suite 422 passed, 17 skipped, 47 xfailed. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> commit-id:be96f1da
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What
When
POLISMATH_ENGINE_MODE=clojure-legacy(the engine setting that reproduces the old Clojure engine's behavior exactly), the previous tick's unit PCA components are threaded into the power-iteration PCA as start vectors, matching Clojure (conversation.clj:381-387passes:start-vectors (get-in conv [:pca :comps])intopowerit-pca,pca.clj:86-105; new columns are absorbed by 1-padding,pca.clj:46-49). Defaultimprovedmode is unchanged (cold recompute).Changes
pca_project_dataframegainsstart_vectors(defaultNone) andrequire_powerit(defaultFalse). With both absent, the code path is BYTE-IDENTICAL to before. When a warm start is supplied — or required by legacy mode — andPOLISMATH_PCA_IMPL=sklearnis set, we warn and fall back to power iteration: sklearn's SVD has no start-vector hook, so running it would silently drop the warm start (documented at the guard).powerit_pcaalready supportedstart_vectors+ 1-padding + all-zero ->None; this just wires the production callers to it.Conversation._compute_pca: in legacy mode setsrequire_powerit=Trueand, whenprev_pcahas real components,start_vectors= the previous components (empty/cold ->None, which yields the deterministic random cold draw).prev_pcais captured inrecompute()(PR-A, the previous commit in this series).Semantic judgment calls (integrator, please verify vs Clojure)
_power_iterationtruncates a too-long start vector defensively (pre-existing,pca.py:124-127) where Clojure would error.require_powerit=Trueeven on the cold first tick, so an operator settingPCA_IMPL=sklearn+ legacy still gets power iteration (with a warning).Testing
TDD RED evidence (before implementing):
test_start_vectors_reach_powerit— "TypeError: pca_project_dataframe() got an unexpected keyword argument 'start_vectors'";test_legacy_tick2_receives_tick1_comps— "assert None is not None" (tick 2 ran cold; no components threaded).Tests: 8 new (start_vectors threading, sklearn-conflict warning, improved-mode byte-identity, two-tick legacy warm start via spy, angle stability, cold-tick cross-mode identity). Full suite 422 passed, 17 skipped, 47 xfailed.
Co-Authored-By: Claude Fable 5 noreply@anthropic.com
commit-id:be96f1da
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