Instead of hardcoding the value of beta1 and beta2 in case of TTUR(Tw…

…o-Timestep Update Rule), change the default values. This modification is for the readability of the code.

models/pix2pix_model.py

@@ -66,11 +66,10 @@ def create_optimizers(self, opt):
         if opt.isTrain:
             D_params = list(self.netD.parameters())
 
+        beta1, beta2 = opt.beta1, opt.beta2
         if opt.no_TTUR:
-            beta1, beta2 = opt.beta1, opt.beta2
             G_lr, D_lr = opt.lr, opt.lr
         else:
-            beta1, beta2 = 0, 0.9
             G_lr, D_lr = opt.lr / 2, opt.lr * 2
 
         optimizer_G = torch.optim.Adam(G_params, lr=G_lr, betas=(beta1, beta2))

options/train_options.py

@@ -24,8 +24,15 @@ def initialize(self, parser):
         parser.add_argument('--niter', type=int, default=50, help='# of iter at starting learning rate. This is NOT the total #epochs. Totla #epochs is niter + niter_decay')
         parser.add_argument('--niter_decay', type=int, default=0, help='# of iter to linearly decay learning rate to zero')
         parser.add_argument('--optimizer', type=str, default='adam')
-        parser.add_argument('--beta1', type=float, default=0.5, help='momentum term of adam')
-        parser.add_argument('--beta2', type=float, default=0.999, help='momentum term of adam')
+        parser.add_argument('--beta1', type=float, default=0.0, help='momentum term of adam')
+        parser.add_argument('--beta2', type=float, default=0.9, help='momentum term of adam')
+        parser.add_argument('--no_TTUR', action='store_true', help='Use TTUR training scheme')
+
+        # the default values for beta1 and beta2 differ by TTUR option
+        opt, _ = parser.parse_known_args()
+        if opt.no_TTUR:
+            parser.set_defaults(beta1=0.5, beta2=0.999)
+
         parser.add_argument('--lr', type=float, default=0.0002, help='initial learning rate for adam')
         parser.add_argument('--D_steps_per_G', type=int, default=1, help='number of discriminator iterations per generator iterations.')
 
@@ -37,7 +44,6 @@ def initialize(self, parser):
         parser.add_argument('--no_vgg_loss', action='store_true', help='if specified, do *not* use VGG feature matching loss')
         parser.add_argument('--gan_mode', type=str, default='hinge', help='(ls|original|hinge)')
         parser.add_argument('--netD', type=str, default='multiscale', help='(n_layers|multiscale|image)')
-        parser.add_argument('--no_TTUR', action='store_true', help='Use TTUR training scheme')
         parser.add_argument('--lambda_kld', type=float, default=0.05)
         self.isTrain = True
         return parser