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Diffstat (limited to 'code/sunlab/suntorch/models/convolutional/variational/autoencoder.py')
| -rw-r--r-- | code/sunlab/suntorch/models/convolutional/variational/autoencoder.py | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/code/sunlab/suntorch/models/convolutional/variational/autoencoder.py b/code/sunlab/suntorch/models/convolutional/variational/autoencoder.py new file mode 100644 index 0000000..970f717 --- /dev/null +++ b/code/sunlab/suntorch/models/convolutional/variational/autoencoder.py @@ -0,0 +1,190 @@ +import torch +from torch import nn + + +class ConvolutionalVariationalAutoencoder(nn.Module): + def __init__(self, latent_dims, hidden_dims, image_shape, dropout=0.0): + super(ConvolutionalVariationalAutoencoder, self).__init__() + + self.latent_dims = latent_dims # Size of the latent space layer + self.hidden_dims = ( + hidden_dims # List of hidden layers number of filters/channels + ) + self.image_shape = image_shape # Input image shape + + self.last_channels = self.hidden_dims[-1] + self.in_channels = self.image_shape[0] + # Simple formula to get the number of neurons after the last convolution layer is flattened + self.flattened_channels = int( + self.last_channels + * (self.image_shape[1] / (2 ** len(self.hidden_dims))) ** 2 + ) + + # For each hidden layer we will create a Convolution Block + modules = [] + for h_dim in self.hidden_dims: + modules.append( + nn.Sequential( + nn.Conv2d( + in_channels=self.in_channels, + out_channels=h_dim, + kernel_size=3, + stride=2, + padding=1, + ), + nn.BatchNorm2d(h_dim), + nn.LeakyReLU(), + nn.Dropout(p=dropout), + ) + ) + + self.in_channels = h_dim + + self.encoder = nn.Sequential(*modules) + + # Here are our layers for our latent space distribution + self.fc_mu = nn.Linear(self.flattened_channels, latent_dims) + self.fc_var = nn.Linear(self.flattened_channels, latent_dims) + + # Decoder input layer + self.decoder_input = nn.Linear(latent_dims, self.flattened_channels) + + # For each Convolution Block created on the Encoder we will do a symmetric Decoder with the same Blocks, but using ConvTranspose + self.hidden_dims.reverse() + modules = [] + for h_dim in self.hidden_dims: + modules.append( + nn.Sequential( + nn.ConvTranspose2d( + in_channels=self.in_channels, + out_channels=h_dim, + kernel_size=3, + stride=2, + padding=1, + output_padding=1, + ), + nn.BatchNorm2d(h_dim), + nn.LeakyReLU(), + nn.Dropout(p=dropout), + ) + ) + + self.in_channels = h_dim + + self.decoder = nn.Sequential(*modules) + + # The final layer the reconstructed image have the same dimensions as the input image + self.final_layer = nn.Sequential( + nn.Conv2d( + in_channels=self.in_channels, + out_channels=self.image_shape[0], + kernel_size=3, + padding=1, + ), + nn.Sigmoid(), + ) + + def get_latent_dims(self): + + return self.latent_dims + + def encode(self, input): + """ + Encodes the input by passing through the encoder network + and returns the latent codes. + """ + result = self.encoder(input) + result = torch.flatten(result, start_dim=1) + # Split the result into mu and var componentsbof the latent Gaussian distribution + mu = self.fc_mu(result) + log_var = self.fc_var(result) + + return [mu, log_var] + + def decode(self, z): + """ + Maps the given latent codes onto the image space. + """ + result = self.decoder_input(z) + result = result.view( + -1, + self.last_channels, + int(self.image_shape[1] / (2 ** len(self.hidden_dims))), + int(self.image_shape[1] / (2 ** len(self.hidden_dims))), + ) + result = self.decoder(result) + result = self.final_layer(result) + + return result + + def reparameterize(self, mu, log_var): + """ + Reparameterization trick to sample from N(mu, var) from N(0,1). + """ + std = torch.exp(0.5 * log_var) + eps = torch.randn_like(std) + + return mu + eps * std + + def forward(self, input): + """ + Forward method which will encode and decode our image. + """ + mu, log_var = self.encode(input) + z = self.reparameterize(mu, log_var) + + return [self.decode(z), input, mu, log_var, z] + + def loss_function(self, recons, input, mu, log_var): + """ + Computes VAE loss function + """ + recons_loss = nn.functional.binary_cross_entropy( + recons.reshape(recons.shape[0], -1), + input.reshape(input.shape[0], -1), + reduction="none", + ).sum(dim=-1) + + kld_loss = -0.5 * torch.sum(1 + log_var - mu.pow(2) - log_var.exp(), dim=-1) + + loss = (recons_loss + kld_loss).mean(dim=0) + + return loss + + def sample(self, num_samples, device): + """ + Samples from the latent space and return the corresponding + image space map. + """ + z = torch.randn(num_samples, self.latent_dims) + z = z.to(device) + samples = self.decode(z) + + return samples + + def generate(self, x): + """ + Given an input image x, returns the reconstructed image + """ + return self.forward(x)[0] + + def interpolate(self, starting_inputs, ending_inputs, device, granularity=10): + """This function performs a linear interpolation in the latent space of the autoencoder + from starting inputs to ending inputs. It returns the interpolation trajectories. + """ + mu, log_var = self.encode(starting_inputs.to(device)) + starting_z = self.reparameterize(mu, log_var) + + mu, log_var = self.encode(ending_inputs.to(device)) + ending_z = self.reparameterize(mu, log_var) + + t = torch.linspace(0, 1, granularity).to(device) + + intep_line = torch.kron( + starting_z.reshape(starting_z.shape[0], -1), (1 - t).unsqueeze(-1) + ) + torch.kron(ending_z.reshape(ending_z.shape[0], -1), t.unsqueeze(-1)) + + decoded_line = self.decode(intep_line).reshape( + (starting_inputs.shape[0], t.shape[0]) + (starting_inputs.shape[1:]) + ) + return decoded_line |