update partial block merge method

 * more flexible partial update. only the first model(model_a) need to be the same.
 * simplified modified blocks check method.

scripts/model_mixer.py

@@ -2506,33 +2506,50 @@ def add_difference(theta0, theta1, base, alpha):
         if use_unet_partial_update and current is not None:
             # check same models used
             hashes = current["hashes"]
-            same_models = True
-            if len(hashes) != len(mm_models) + 1:
-                same_models = False
-            for j, m in enumerate([model_a] + [*mm_models]):
-                info = sd_models.get_closet_checkpoint_match(m)
-                if info is None:
-                    same_models = False
-                    break
+            # only the first model need to be checked
+            first_model_is_the_same = False
+
+            # check model_a
+            info = sd_models.get_closet_checkpoint_match(model_a)
+            if info is not None:
                 if info.shorthash is None:
                     info.calculate_shorthash()
-                if j >= len(hashes) or hashes[j] != info.shorthash:
-                    same_models = False
-                    break
-
-            if same_models:
-                print(" - check possible UNet partial update...")
-
-            if same_models and current["calcmode"] == mm_calcmodes and current["mode"] == mm_modes:
-                max_blocks = 26 - (0 if not isxl else 6)
-
-                # check changed weights
-                weights = current["weights"]
-                while len(weights) > 0:
-                    changed = [False] * len(weights[0])
-                    for j, w in enumerate(mm_weights):
-                        changed |= np.array(weights[j][:max_blocks]) != np.array(w[:max_blocks])
+                if hashes[0] == info.shorthash:
+                    first_model_is_the_same = True
+
+                if first_model_is_the_same:
+                    print(" - check possible UNet partial update...")
+                    max_blocks = 26 - (0 if not isxl else 6)
+
+                    # check changed weights
+                    weights = current["weights"]
+                    changed = [False] * max_blocks
+
+                    for j, m in enumerate(mm_models):
+                        info = sd_models.get_closet_checkpoint_match(m)
+                        if info is None:
+                            if info.shorthash is None:
+                                info.calculate_shorthash()
+
+                        same_model = True
+                        # is it different model?
+                        if j + 1 >= len(hashes) or hashes[j + 1] != info.shorthash:
+                            same_model = False
+
+                        if same_model and (current["calcmode"][j] != mm_calcmodes[j] or current["mode"][j] != mm_modes[j]):
+                            same_model = False
+
+                        if same_model:
+                            # check modified block weighs
+                            changed |= np.array(weights[j][:max_blocks]) != np.array(mm_weights[j][:max_blocks])
+                        else:
+                            # check all non zero blocks
+                            if len(weights) > j:
+                                changed |= np.array(weights[j][:max_blocks]) != np.array([0.0]*max_blocks)
+                            changed |= np.array(mm_weights[j][:max_blocks]) != np.array([0.0]*max_blocks)
 
+                    BLOCKIDS = BLOCKID if not isxl else BLOCKIDXL
+                    print(" - partial changed blocks = ", [BLOCKIDS[k] for k, b in enumerate(changed) if b])
                     all_blocks = _all_blocks(isxl)
                     weight_changed_blocks = []
                     for j, b in enumerate(changed):
@@ -2573,8 +2590,6 @@ def add_difference(theta0, theta1, base, alpha):
                         partial_update = True
                         print(" - UNet partial update mode")
 
-                    break
-
         # check Rebasin mode
         if not isxl and "Rebasin" in calcmodes:
             print("Rebasin mode")