motief/thoughts/ledgers/CONTINUITY_svd_axis_consistency_fix.md

Session: svd_axis_consistency_fix

Updated: 2026-04-13T23:08:19Z

Goal

Ensure SVD components tab and compass show consistent party positions by using aligned PCA positions for components 1-2.

Constraints

• Right-wing parties (PVV, FVD, JA21, SGP) must appear on RIGHT side of all axes in both visualizations
• SVD labels should reflect voting patterns, not semantic content
• Components 1-2 use aligned PCA; Components 3-10 use raw SVD values

Progress

Done

• Fix SVD axis label alignment (removed static left_pole/right_pole, derive from runtime flip)
• Fix score mismatch in tijdtraject view (components 3-10 use per-window scores, not Procrustes-aligned)
• Fix PCA alignment consistency between compass and SVD components tab
• Update all 10 component labels based on motion analysis
• Add pool-based motion assignment (10 motions per component)
• Add SVD axis alignment and label consistency tests

In Progress

• (none)

Blocked

• (none)

Key Decisions

• Components 1-2 use aligned PCA positions: Consistent with compass visualization, derived from load_positions()
• Components 3-10 use raw SVD scores: Per-window flip handles orientation, Procrustes not needed
• New helper _get_aligned_party_coords(): Converts aligned MP positions to party centroids for components 1-2

Next Steps

1. Run visual verification to confirm compass and SVD tab show consistent party orderings
2. Consider adding tests for the new _get_aligned_party_coords() helper
3. Update any documentation that references the old behavior

File Operations

Read

• explorer.py (components tab, load_positions, trajectory rendering)
• analysis/political_axis.py (PCA alignment, compute_party_centroids)
• analysis/config.py (SVD_THEMES)
• analysis/svd_labels.py (label derivation)

Modified

• explorer.py - Added _get_aligned_party_coords(), updated component 1-2 to use aligned positions

Critical Context

• Commit 823df6f: Removed static left_pole/right_pole, fixed tijdtraject score mismatch
• Commit 12936c5: Use aligned PCA for components 1-2 (consistent with compass)
• Commit 036c3f9: Extended aligned PCA to all SVD components 1-10
• Commit 3a67100: Use aligned PCA scores for time trajectory view
• Related docs: docs/solutions/ui-bugs/svd-axis-pole-labels-incorrect-after-flip.md

Working Set

• Branch: main
• Key files: explorer.py, analysis/config.py, analysis/svd_labels.py, tests/test_svd_axis_alignment.py