From 13b0d9f763269df405d1aeba86213f1c7ce4e7ca Mon Sep 17 00:00:00 2001
From: Volpeon <git@volpeon.ink>
Date: Sun, 2 Oct 2022 15:14:29 +0200
Subject: More consistent euler_a

---
 schedulers/scheduling_euler_a.py | 59 ++++++++++++++++++----------------------
 1 file changed, 26 insertions(+), 33 deletions(-)

(limited to 'schedulers')

diff --git a/schedulers/scheduling_euler_a.py b/schedulers/scheduling_euler_a.py
index 9fbedaa..1b1c9cf 100644
--- a/schedulers/scheduling_euler_a.py
+++ b/schedulers/scheduling_euler_a.py
@@ -1,7 +1,3 @@
-
-
-import math
-import warnings
 from typing import Optional, Tuple, Union
 
 import numpy as np
@@ -157,9 +153,6 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
         beta_end: float = 0.02,
         beta_schedule: str = "linear",
         trained_betas: Optional[np.ndarray] = None,
-        clip_sample: bool = True,
-        set_alpha_to_one: bool = True,
-        steps_offset: int = 0,
     ):
         if trained_betas is not None:
             self.betas = torch.from_numpy(trained_betas)
@@ -177,12 +170,6 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
         self.alphas = 1.0 - self.betas
         self.alphas_cumprod = torch.cumprod(self.alphas, dim=0)
 
-        # At every step in ddim, we are looking into the previous alphas_cumprod
-        # For the final step, there is no previous alphas_cumprod because we are already at 0
-        # `set_alpha_to_one` decides whether we set this parameter simply to one or
-        # whether we use the final alpha of the "non-previous" one.
-        self.final_alpha_cumprod = torch.tensor(1.0) if set_alpha_to_one else self.alphas_cumprod[0]
-
         # setable values
         self.num_inference_steps = None
         self.timesteps = np.arange(0, num_train_timesteps)[::-1]
@@ -199,21 +186,10 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
                 the number of diffusion steps used when generating samples with a pre-trained model.
         """
 
-        # offset = self.config.steps_offset
-
-        # if "offset" in kwargs:
-        #     warnings.warn(
-        #         "`offset` is deprecated as an input argument to `set_timesteps` and will be removed in v0.4.0."
-        #         " Please pass `steps_offset` to `__init__` instead.",
-        #         DeprecationWarning,
-        #     )
-
-        #     offset = kwargs["offset"]
-
         self.num_inference_steps = num_inference_steps
         self.DSsigmas = ((1 - self.alphas_cumprod) / self.alphas_cumprod) ** 0.5
-        self.sigmas = get_sigmas(self.DSsigmas, self.num_inference_steps - 1).to(device=device)
-        self.timesteps = self.sigmas
+        self.sigmas = get_sigmas(self.DSsigmas, self.num_inference_steps).to(device=device)
+        self.timesteps = np.arange(0, self.num_inference_steps)
 
     def add_noise_to_input(
         self, sample: torch.FloatTensor, sigma: float, generator: Optional[torch.Generator] = None
@@ -239,8 +215,8 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
     def step(
         self,
         model_output: torch.FloatTensor,
-        timestep: torch.IntTensor,
-        timestep_prev: torch.IntTensor,
+        timestep: int,
+        timestep_prev: int,
         sample: torch.FloatTensor,
         generator: None,
         # ,sigma_hat: float,
@@ -266,13 +242,17 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
             returning a tuple, the first element is the sample tensor.
 
         """
+        s = self.sigmas[timestep]
+        s_prev = self.sigmas[timestep_prev]
         latents = sample
-        sigma_down, sigma_up = get_ancestral_step(timestep, timestep_prev)
-        d = to_d(latents, timestep, model_output)
-        dt = sigma_down - timestep
+
+        sigma_down, sigma_up = get_ancestral_step(s, s_prev)
+        d = to_d(latents, s, model_output)
+        dt = sigma_down - s
         latents = latents + d * dt
         latents = latents + torch.randn(latents.shape, layout=latents.layout, device=latents.device,
                                         generator=generator) * sigma_up
+
         return SchedulerOutput(prev_sample=latents)
 
     def step_correct(
@@ -311,5 +291,18 @@ class EulerAScheduler(SchedulerMixin, ConfigMixin):
 
         return SchedulerOutput(prev_sample=sample_prev)
 
-    def add_noise(self, original_samples, noise, timesteps):
-        raise NotImplementedError()
+    def add_noise(
+        self,
+        original_samples: torch.FloatTensor,
+        noise: torch.FloatTensor,
+        timesteps: torch.IntTensor,
+    ) -> torch.FloatTensor:
+        sigmas = self.sigmas.to(original_samples.device)
+        timesteps = timesteps.to(original_samples.device)
+
+        sigma = sigmas[timesteps].flatten()
+        while len(sigma.shape) < len(original_samples.shape):
+            sigma = sigma.unsqueeze(-1)
+
+        noisy_samples = original_samples + noise * sigma
+        return noisy_samples
-- 
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