Add support for checkpoint merging

modules/extras.py

@@ -3,6 +3,8 @@ import os
 import numpy as np
 from PIL import Image
 
+import torch
+
 from modules import processing, shared, images, devices
 from modules.shared import opts
 import modules.gfpgan_model
@@ -135,3 +137,25 @@ def run_pnginfo(image):
         info = f"<div><p>{message}<p></div>"
 
     return '', geninfo, info
+
+
+def run_modelmerger(modelname_0, modelname_1, alpha):
+    model_0 = torch.load('models/' + modelname_0 + '.ckpt')
+    model_1 = torch.load('models/' + modelname_1 + '.ckpt')
+    
+    theta_0 = model_0['state_dict']
+    theta_1 = model_1['state_dict']
+    
+    for key in theta_0.keys():
+        if 'model' in key and key in theta_1:
+            theta_0[key] = (1 - alpha) * theta_0[key] + alpha * theta_1[key]
+    
+    for key in theta_1.keys():
+        if 'model' in key and key not in theta_0:
+            theta_0[key] = theta_1[key]
+    
+    output_modelname = 'models/' + modelname_0 + '-' + modelname_1 + '-merged.ckpt';
+    
+    torch.save(model_0, output_modelname)
+    
+    return "<p>Model saved to " + output_modelname + "</p>"