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| """SAMPLING ONLY.""" | |
| import torch | |
| import numpy as np | |
| from tqdm import tqdm | |
| from functools import partial | |
| from util import make_ddim_sampling_parameters, make_ddim_timesteps, noise_like | |
| class PLMSSampler(object): | |
| def __init__(self, model, schedule="linear", **kwargs): | |
| super().__init__() | |
| self.model = model | |
| self.ddpm_num_timesteps = model.num_timesteps | |
| self.schedule = schedule | |
| def register_buffer(self, name, attr): | |
| if type(attr) == torch.Tensor: | |
| if attr.device != torch.device("cuda"): | |
| attr = attr.to(torch.device("cuda")) | |
| setattr(self, name, attr) | |
| def make_schedule(self, ddim_num_steps, ddim_discretize="uniform", ddim_eta=0., verbose=True): | |
| if ddim_eta != 0: | |
| raise ValueError('ddim_eta must be 0 for PLMS') | |
| self.ddim_timesteps = make_ddim_timesteps(ddim_discr_method=ddim_discretize, num_ddim_timesteps=ddim_num_steps, | |
| num_ddpm_timesteps=self.ddpm_num_timesteps,verbose=verbose) | |
| alphas_cumprod = self.model.alphas_cumprod | |
| assert alphas_cumprod.shape[0] == self.ddpm_num_timesteps, 'alphas have to be defined for each timestep' | |
| to_torch = lambda x: x.clone().detach().to(torch.float32).to(self.model.device) | |
| self.register_buffer('betas', to_torch(self.model.betas)) | |
| self.register_buffer('alphas_cumprod', to_torch(alphas_cumprod)) | |
| self.register_buffer('alphas_cumprod_prev', to_torch(self.model.alphas_cumprod_prev)) | |
| # calculations for diffusion q(x_t | x_{t-1}) and others | |
| self.register_buffer('sqrt_alphas_cumprod', to_torch(np.sqrt(alphas_cumprod.cpu()))) | |
| self.register_buffer('sqrt_one_minus_alphas_cumprod', to_torch(np.sqrt(1. - alphas_cumprod.cpu()))) | |
| self.register_buffer('log_one_minus_alphas_cumprod', to_torch(np.log(1. - alphas_cumprod.cpu()))) | |
| self.register_buffer('sqrt_recip_alphas_cumprod', to_torch(np.sqrt(1. / alphas_cumprod.cpu()))) | |
| self.register_buffer('sqrt_recipm1_alphas_cumprod', to_torch(np.sqrt(1. / alphas_cumprod.cpu() - 1))) | |
| # ddim sampling parameters | |
| ddim_sigmas, ddim_alphas, ddim_alphas_prev = make_ddim_sampling_parameters(alphacums=alphas_cumprod.cpu(), | |
| ddim_timesteps=self.ddim_timesteps, | |
| eta=ddim_eta,verbose=verbose) | |
| self.register_buffer('ddim_sigmas', ddim_sigmas) | |
| self.register_buffer('ddim_alphas', ddim_alphas) | |
| self.register_buffer('ddim_alphas_prev', ddim_alphas_prev) | |
| self.register_buffer('ddim_sqrt_one_minus_alphas', np.sqrt(1. - ddim_alphas)) | |
| sigmas_for_original_sampling_steps = ddim_eta * torch.sqrt( | |
| (1 - self.alphas_cumprod_prev) / (1 - self.alphas_cumprod) * ( | |
| 1 - self.alphas_cumprod / self.alphas_cumprod_prev)) | |
| self.register_buffer('ddim_sigmas_for_original_num_steps', sigmas_for_original_sampling_steps) | |
| def sample(self, | |
| S, | |
| batch_size, | |
| shape, | |
| conditioning=None, | |
| callback=None, | |
| normals_sequence=None, | |
| img_callback=None, | |
| quantize_x0=False, | |
| eta=0., | |
| mask=None, | |
| x0=None, | |
| temperature=1., | |
| noise_dropout=0., | |
| score_corrector=None, | |
| corrector_kwargs=None, | |
| verbose=True, | |
| x_T=None, | |
| log_every_t=100, | |
| unconditional_guidance_scale=1., | |
| unconditional_conditioning=None, | |
| # this has to come in the same format as the conditioning, # e.g. as encoded tokens, ... | |
| **kwargs | |
| ): | |
| if conditioning is not None: | |
| if isinstance(conditioning, dict): | |
| cbs = conditioning[list(conditioning.keys())[0]].shape[0] | |
| if cbs != batch_size: | |
| print(f"Warning: Got {cbs} conditionings but batch-size is {batch_size}") | |
| else: | |
| if conditioning.shape[0] != batch_size: | |
| print(f"Warning: Got {conditioning.shape[0]} conditionings but batch-size is {batch_size}") | |
| self.make_schedule(ddim_num_steps=S, ddim_eta=eta, verbose=verbose) | |
| # sampling | |
| C, H, W = shape | |
| size = (batch_size, C, H, W) | |
| print(f'Data shape for PLMS sampling is {size}') | |
| samples, intermediates = self.plms_sampling(conditioning, size, | |
| callback=callback, | |
| img_callback=img_callback, | |
| quantize_denoised=quantize_x0, | |
| mask=mask, x0=x0, | |
| ddim_use_original_steps=False, | |
| noise_dropout=noise_dropout, | |
| temperature=temperature, | |
| score_corrector=score_corrector, | |
| corrector_kwargs=corrector_kwargs, | |
| x_T=x_T, | |
| log_every_t=log_every_t, | |
| unconditional_guidance_scale=unconditional_guidance_scale, | |
| unconditional_conditioning=unconditional_conditioning, | |
| ) | |
| return samples, intermediates | |
| def plms_sampling(self, cond, shape, | |
| x_T=None, ddim_use_original_steps=False, | |
| callback=None, timesteps=None, quantize_denoised=False, | |
| mask=None, x0=None, img_callback=None, log_every_t=100, | |
| temperature=1., noise_dropout=0., score_corrector=None, corrector_kwargs=None, | |
| unconditional_guidance_scale=1., unconditional_conditioning=None,): | |
| device = self.model.betas.device | |
| b = shape[0] | |
| if x_T is None: | |
| img = torch.randn(shape, device=device) | |
| else: | |
| img = x_T | |
| if timesteps is None: | |
| timesteps = self.ddpm_num_timesteps if ddim_use_original_steps else self.ddim_timesteps | |
| elif timesteps is not None and not ddim_use_original_steps: | |
| subset_end = int(min(timesteps / self.ddim_timesteps.shape[0], 1) * self.ddim_timesteps.shape[0]) - 1 | |
| timesteps = self.ddim_timesteps[:subset_end] | |
| intermediates = {'x_inter': [img], 'pred_x0': [img]} | |
| time_range = list(reversed(range(0,timesteps))) if ddim_use_original_steps else np.flip(timesteps) | |
| total_steps = timesteps if ddim_use_original_steps else timesteps.shape[0] | |
| print(f"Running PLMS Sampling with {total_steps} timesteps") | |
| iterator = tqdm(time_range, desc='PLMS Sampler', total=total_steps) | |
| old_eps = [] | |
| for i, step in enumerate(iterator): | |
| index = total_steps - i - 1 | |
| ts = torch.full((b,), step, device=device, dtype=torch.long) | |
| ts_next = torch.full((b,), time_range[min(i + 1, len(time_range) - 1)], device=device, dtype=torch.long) | |
| if mask is not None: | |
| assert x0 is not None | |
| img_orig = self.model.q_sample(x0, ts) # TODO: deterministic forward pass? | |
| img = img_orig * mask + (1. - mask) * img | |
| outs = self.p_sample_plms(img, cond, ts, index=index, use_original_steps=ddim_use_original_steps, | |
| quantize_denoised=quantize_denoised, temperature=temperature, | |
| noise_dropout=noise_dropout, score_corrector=score_corrector, | |
| corrector_kwargs=corrector_kwargs, | |
| unconditional_guidance_scale=unconditional_guidance_scale, | |
| unconditional_conditioning=unconditional_conditioning, | |
| old_eps=old_eps, t_next=ts_next) | |
| img, pred_x0, e_t = outs | |
| old_eps.append(e_t) | |
| if len(old_eps) >= 4: | |
| old_eps.pop(0) | |
| if callback: callback(i) | |
| if img_callback: img_callback(pred_x0, i) | |
| if index % log_every_t == 0 or index == total_steps - 1: | |
| intermediates['x_inter'].append(img) | |
| intermediates['pred_x0'].append(pred_x0) | |
| return img, intermediates | |
| def p_sample_plms(self, x, c, t, index, repeat_noise=False, use_original_steps=False, quantize_denoised=False, | |
| temperature=1., noise_dropout=0., score_corrector=None, corrector_kwargs=None, | |
| unconditional_guidance_scale=1., unconditional_conditioning=None, old_eps=None, t_next=None): | |
| b, *_, device = *x.shape, x.device | |
| def get_model_output(x, t): | |
| if unconditional_conditioning is None or unconditional_guidance_scale == 1.: | |
| e_t = self.model.apply_model(x, t, c) | |
| else: | |
| x_in = torch.cat([x] * 2) | |
| t_in = torch.cat([t] * 2) | |
| c_in = torch.cat([unconditional_conditioning, c]) | |
| e_t_uncond, e_t = self.model.apply_model(x_in, t_in, c_in).chunk(2) | |
| e_t = e_t_uncond + unconditional_guidance_scale * (e_t - e_t_uncond) | |
| if score_corrector is not None: | |
| assert self.model.parameterization == "eps" | |
| e_t = score_corrector.modify_score(self.model, e_t, x, t, c, **corrector_kwargs) | |
| return e_t | |
| alphas = self.model.alphas_cumprod if use_original_steps else self.ddim_alphas | |
| alphas_prev = self.model.alphas_cumprod_prev if use_original_steps else self.ddim_alphas_prev | |
| sqrt_one_minus_alphas = self.model.sqrt_one_minus_alphas_cumprod if use_original_steps else self.ddim_sqrt_one_minus_alphas | |
| sigmas = self.model.ddim_sigmas_for_original_num_steps if use_original_steps else self.ddim_sigmas | |
| def get_x_prev_and_pred_x0(e_t, index): | |
| # select parameters corresponding to the currently considered timestep | |
| a_t = torch.full((b, 1, 1, 1), alphas[index], device=device) | |
| a_prev = torch.full((b, 1, 1, 1), alphas_prev[index], device=device) | |
| sigma_t = torch.full((b, 1, 1, 1), sigmas[index], device=device) | |
| sqrt_one_minus_at = torch.full((b, 1, 1, 1), sqrt_one_minus_alphas[index],device=device) | |
| # current prediction for x_0 | |
| pred_x0 = (x - sqrt_one_minus_at * e_t) / a_t.sqrt() | |
| if quantize_denoised: | |
| pred_x0, _, *_ = self.model.first_stage_model.quantize(pred_x0) | |
| # direction pointing to x_t | |
| dir_xt = (1. - a_prev - sigma_t**2).sqrt() * e_t | |
| noise = sigma_t * noise_like(x.shape, device, repeat_noise) * temperature | |
| if noise_dropout > 0.: | |
| noise = torch.nn.functional.dropout(noise, p=noise_dropout) | |
| x_prev = a_prev.sqrt() * pred_x0 + dir_xt + noise | |
| return x_prev, pred_x0 | |
| e_t = get_model_output(x, t) | |
| if len(old_eps) == 0: | |
| # Pseudo Improved Euler (2nd order) | |
| x_prev, pred_x0 = get_x_prev_and_pred_x0(e_t, index) | |
| e_t_next = get_model_output(x_prev, t_next) | |
| e_t_prime = (e_t + e_t_next) / 2 | |
| elif len(old_eps) == 1: | |
| # 2nd order Pseudo Linear Multistep (Adams-Bashforth) | |
| e_t_prime = (3 * e_t - old_eps[-1]) / 2 | |
| elif len(old_eps) == 2: | |
| # 3nd order Pseudo Linear Multistep (Adams-Bashforth) | |
| e_t_prime = (23 * e_t - 16 * old_eps[-1] + 5 * old_eps[-2]) / 12 | |
| elif len(old_eps) >= 3: | |
| # 4nd order Pseudo Linear Multistep (Adams-Bashforth) | |
| e_t_prime = (55 * e_t - 59 * old_eps[-1] + 37 * old_eps[-2] - 9 * old_eps[-3]) / 24 | |
| x_prev, pred_x0 = get_x_prev_and_pred_x0(e_t_prime, index) | |
| return x_prev, pred_x0, e_t | |