| 64 | } |
| 65 | |
| 66 | static TVector<TFeaturePathElement> UnwindFeaturePath( |
| 67 | const TVector<TFeaturePathElement>& oldFeaturePath, |
| 68 | size_t eraseElementIdx) |
| 69 | { |
| 70 | const size_t pathLength = oldFeaturePath.size(); |
| 71 | CB_ENSURE(pathLength > 0, "Path to unwind must have at least one element"); |
| 72 | |
| 73 | TVector<TFeaturePathElement> newFeaturePath( |
| 74 | oldFeaturePath.begin(), |
| 75 | oldFeaturePath.begin() + pathLength - 1); |
| 76 | |
| 77 | for (size_t elementIdx = eraseElementIdx; elementIdx < pathLength - 1; ++elementIdx) { |
| 78 | newFeaturePath[elementIdx].Feature = oldFeaturePath[elementIdx + 1].Feature; |
| 79 | newFeaturePath[elementIdx].ZeroPathsFraction = oldFeaturePath[elementIdx + 1].ZeroPathsFraction; |
| 80 | newFeaturePath[elementIdx].OnePathsFraction = oldFeaturePath[elementIdx + 1].OnePathsFraction; |
| 81 | } |
| 82 | |
| 83 | const double onePathsFraction = oldFeaturePath[eraseElementIdx].OnePathsFraction; |
| 84 | const double zeroPathsFraction = oldFeaturePath[eraseElementIdx].ZeroPathsFraction; |
| 85 | double weightDiff = oldFeaturePath[pathLength - 1].Weight; |
| 86 | |
| 87 | if (!FuzzyEquals(1 + onePathsFraction, 1 + 0.0)) { |
| 88 | for (int elementIdx = pathLength - 2; elementIdx >= 0; --elementIdx) { |
| 89 | double oldWeight = newFeaturePath[elementIdx].Weight; |
| 90 | newFeaturePath[elementIdx].Weight = weightDiff * pathLength |
| 91 | / (onePathsFraction * (elementIdx + 1)); |
| 92 | weightDiff = oldWeight |
| 93 | - newFeaturePath[elementIdx].Weight * zeroPathsFraction * (pathLength - elementIdx - 1) |
| 94 | / pathLength; |
| 95 | } |
| 96 | } else { |
| 97 | for (int elementIdx = pathLength - 2; elementIdx >= 0; --elementIdx) { |
| 98 | newFeaturePath[elementIdx].Weight *= pathLength |
| 99 | / (zeroPathsFraction * (pathLength - elementIdx - 1)); |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | return newFeaturePath; |
| 104 | } |
| 105 | |
| 106 | static void UpdateShapByFeaturePath( |
| 107 | const TVector<TFeaturePathElement>& featurePath, |
no test coverage detected