bring back old impl of train diff and add new methods (#35)

sd_mecha/merge_methods.py

@@ -273,11 +273,48 @@ def train_difference(
     *,
     alpha: Hyper = 1.0,
     **kwargs,
+) -> Tensor | SameMergeSpace:
+    mask = 1.8 * torch.nan_to_num(torch.abs(b - a) / (torch.abs(b - a) + torch.abs(b - c)), nan=0)
+    return a + (b - c) * alpha * mask
+
+
+@convert_to_recipe
+def add_opposite(
+    a: Tensor | SameMergeSpace,
+    b: Tensor | SameMergeSpace,
+    c: Tensor | SameMergeSpace,
+    *,
+    alpha: Hyper = 1.0,
+    **kwargs,
 ) -> Tensor | SameMergeSpace:
     threshold = torch.maximum(torch.abs(a - c), torch.abs(b - c))
-    dissimilarity = torch.clamp(torch.nan_to_num((c - a) * (b - c) / threshold**2, nan=0), 0)
+    mask = 1 - torch.nan_to_num((a - c) * (b - c) / threshold**2, nan=0)
+    return a + (b - c) * alpha * mask
 
-    return a + (b - c) * alpha * dissimilarity
+
+@convert_to_recipe
+def clamped_add_opposite(
+    a: Tensor | SameMergeSpace,
+    b: Tensor | SameMergeSpace,
+    c: Tensor | SameMergeSpace,
+    *,
+    alpha: Hyper = 1.0,
+    **kwargs,
+) -> Tensor | SameMergeSpace:
+    threshold = torch.maximum(torch.abs(a - c), torch.abs(b - c))
+    mask = torch.clamp(torch.nan_to_num((c - a) * (b - c) / threshold**2, nan=0), 0) * 2
+    return a + (b - c) * alpha * mask
+
+
+@convert_to_recipe
+def select_max_delta(
+    a: Tensor | LiftFlag[MergeSpace.DELTA],
+    b: Tensor | LiftFlag[MergeSpace.DELTA],
+    *,
+    alpha: Hyper = 0.5,
+    **kwargs,
+) -> Tensor | LiftFlag[MergeSpace.DELTA]:
+    return torch.where((1 - alpha) * a.abs() >= alpha * b.abs(), a, b)
 
 
 @convert_to_recipe