Language translation example added (#1131)

README.md

@@ -29,7 +29,8 @@ https://pytorch.org/examples/
 - [PyTorch Module Transformations using fx](./fx/README.md)
 - Distributed PyTorch examples with [Distributed Data Parallel](./distributed/ddp/README.md) and [RPC](./distributed/rpc)
 - [Several examples illustrating the C++ Frontend](cpp)
-- [Image Classification Using Forward-Forward ](./mnist_forward_forward/README.md)
+- [Image Classification Using Forward-Forward](./mnist_forward_forward/README.md)
+- [Language Translation using Transformers](./language_translation/README.md)
 
 
 

language_translation/README.md

@@ -0,0 +1,49 @@
+# Language Translation
+
+This example shows how one might use transformers for language translation. In particular, this implementation is loosely based on the [Attention is All You Need paper](https://arxiv.org/abs/1706.03762).
+
+## Requirements
+
+We will need a tokenizer for our languages. Torchtext does include a tokenizer for English, but unfortunately, we will need more languages then that. We can get these tokenizers via ```spacy```
+
+```bash
+python3 -m spacy download <language>
+python3 -m spacy download en
+python3 -m spacy download de
+```
+
+Spacy supports many languages. For a full accounting of supported languages, please look [here](https://spacy.io/usage/models). This example will default from German to English.
+
+Torchtext is also required:
+```bash
+pip install torchtext
+```
+
+Just running these commands will get you started:
+```bash
+pip install -r requirements.txt
+python3 -m spacy download <language-you-want>
+```
+
+## Usage
+
+This example contains a lot of flags that you can set to change the behavior / training of the module. You can see all of them by running:
+
+```bash
+python3 main.py -h
+```
+
+But in general, all of the settings have "sensible" defaults; however, the default translation is to translate from German to English. To *train* the model, you only need to run the following command, but there is also an example for how to use any language you want:
+
+```bash
+python3 main.py
+python3 main.py --src en --tgt fr # For english to french translation
+```
+
+For model inference, you can use this command:
+
+```bash
+python3 main.py --inference --model_path <path-to-model>
+```
+
+After some loading time, this will open an interactive interface where you can type in whatever sentence you are interested in translating.

language_translation/main.py

@@ -0,0 +1,306 @@
+from time import time # Track how long an epoch takes
+import os # Creating and finding files/directories
+import logging # Logging tools
+from datetime import date # Logging the date for model versioning
+
+import torch # For ML
+from tqdm import tqdm # For fancy progress bars
+
+from src.model import Translator # Our model
+from src.data import get_data, create_mask, generate_square_subsequent_mask # Loading data and data preprocessing
+from argparse import ArgumentParser # For args
+
+# Train on the GPU if possible
+DEVICE = torch.device("cuda" if torch.cuda.is_available() else "cpu")
+
+# Function to generate output sequence using greedy algorithm
+def greedy_decode(model, src, src_mask, max_len, start_symbol, end_symbol):
+
+    # Move to device
+    src = src.to(DEVICE)
+    src_mask = src_mask.to(DEVICE)
+
+    # Encode input
+    memory = model.encode(src, src_mask)
+
+    # Output will be stored here
+    ys = torch.ones(1, 1).fill_(start_symbol).type(torch.long).to(DEVICE)
+
+    # For each element in our translation (which could range up to the maximum translation length)
+    for _ in range(max_len-1):
+
+        # Decode the encoded representation of the input
+        memory = memory.to(DEVICE)
+        tgt_mask = (generate_square_subsequent_mask(ys.size(0), DEVICE).type(torch.bool)).to(DEVICE)
+        out = model.decode(ys, memory, tgt_mask)
+
+        # Reshape
+        out = out.transpose(0, 1)
+
+        # Covert to probabilities and take the max of these probabilities
+        prob = model.ff(out[:, -1])
+        _, next_word = torch.max(prob, dim=1)
+        next_word = next_word.item()
+
+        # Now we have an output which is the vector representation of the translation
+        ys = torch.cat([ys, torch.ones(1, 1).type_as(src.data).fill_(next_word)], dim=0)
+        if next_word == end_symbol:
+            break
+
+    return ys
+
+# Opens an user interface where users can translate an arbitrary sentence
+def inference(opts):
+
+    # Get training data, tokenizer and vocab
+    # objects as well as any special symbols we added to our dataset
+    _, _, src_vocab, tgt_vocab, src_transform, _, special_symbols = get_data(opts)
+
+    src_vocab_size = len(src_vocab)
+    tgt_vocab_size = len(tgt_vocab)
+
+    # Create model
+    model = Translator(
+        num_encoder_layers=opts.enc_layers,
+        num_decoder_layers=opts.dec_layers,
+        embed_size=opts.embed_size,
+        num_heads=opts.attn_heads,
+        src_vocab_size=src_vocab_size,
+        tgt_vocab_size=tgt_vocab_size,
+        dim_feedforward=opts.dim_feedforward,
+        dropout=opts.dropout
+    ).to(DEVICE)
+
+    # Load in weights
+    model.load_state_dict(torch.load(opts.model_path))
+
+    # Set to inference
+    model.eval()
+
+    # Accept input and keep translating until they quit
+    while True:
+        print("> ", end="")
+
+        sentence = input()
+
+        # Convert to tokens
+        src = src_transform(sentence).view(-1, 1)
+        num_tokens = src.shape[0]
+
+        src_mask = (torch.zeros(num_tokens, num_tokens)).type(torch.bool)
+
+        # Decode
+        tgt_tokens = greedy_decode(
+            model, src, src_mask, max_len=num_tokens+5, start_symbol=special_symbols["<bos>"], end_symbol=special_symbols["<eos>"]
+        ).flatten()
+
+        # Convert to list of tokens
+        output_as_list = list(tgt_tokens.cpu().numpy())
+
+        # Convert tokens to words
+        output_list_words = tgt_vocab.lookup_tokens(output_as_list)
+
+        # Remove special tokens and convert to string
+        translation = " ".join(output_list_words).replace("<bos>", "").replace("<eos>", "")
+
+        print(translation)
+
+# Train the model for 1 epoch
+def train(model, train_dl, loss_fn, optim, special_symbols, opts):
+
+    # Object for accumulating losses
+    losses = 0
+
+    # Put model into inference mode
+    model.train()
+    for src, tgt in tqdm(train_dl, ascii=True):
+
+        src = src.to(DEVICE)
+        tgt = tgt.to(DEVICE)
+
+        # We need to reshape the input slightly to fit into the transformer
+        tgt_input = tgt[:-1, :]
+
+        # Create masks
+        src_mask, tgt_mask, src_padding_mask, tgt_padding_mask = create_mask(src, tgt_input, special_symbols["<pad>"], DEVICE)
+
+        # Pass into model, get probability over the vocab out
+        logits = model(src, tgt_input, src_mask, tgt_mask,src_padding_mask, tgt_padding_mask, src_padding_mask)
+
+        # Reset gradients before we try to compute the gradients over the loss
+        optim.zero_grad()
+
+        # Get original shape back
+        tgt_out = tgt[1:, :]
+
+        # Compute loss and gradient over that loss
+        loss = loss_fn(logits.reshape(-1, logits.shape[-1]), tgt_out.reshape(-1))
+        loss.backward()
+
+        # Step weights
+        optim.step()
+
+        # Accumulate a running loss for reporting
+        losses += loss.item()
+
+        if opts.dry_run:
+            break
+
+    # Return the average loss
+    return losses / len(list(train_dl))
+
+# Check the model accuracy on the validation dataset
+def validate(model, valid_dl, loss_fn, special_symbols):
+
+    # Object for accumulating losses
+    losses = 0
+
+    # Turn off gradients a moment
+    model.eval()
+
+    for src, tgt in tqdm(valid_dl):
+
+        src = src.to(DEVICE)
+        tgt = tgt.to(DEVICE)
+
+        # We need to reshape the input slightly to fit into the transformer
+        tgt_input = tgt[:-1, :]
+
+        # Create masks
+        src_mask, tgt_mask, src_padding_mask, tgt_padding_mask = create_mask(src, tgt_input, special_symbols["<pad>"], DEVICE)
+
+        # Pass into model, get probability over the vocab out
+        logits = model(src, tgt_input, src_mask, tgt_mask,src_padding_mask, tgt_padding_mask, src_padding_mask)
+
+        # Get original shape back, compute loss, accumulate that loss
+        tgt_out = tgt[1:, :]
+        loss = loss_fn(logits.reshape(-1, logits.shape[-1]), tgt_out.reshape(-1))
+        losses += loss.item()
+
+    # Return the average loss
+    return losses / len(list(valid_dl))
+
+# Train the model
+def main(opts):
+
+    # Set up logging
+    os.makedirs(opts.logging_dir, exist_ok=True)
+    logger = logging.getLogger(__name__)
+    logging.basicConfig(filename=opts.logging_dir + "log.txt", level=logging.INFO)
+
+    # This prints it to the screen as well
+    console = logging.StreamHandler()
+    console.setLevel(logging.INFO)
+    logging.getLogger().addHandler(console)
+
+    logging.info(f"Translation task: {opts.src} -> {opts.tgt}")
+    logging.info(f"Using device: {DEVICE}")
+
+    # Get training data, tokenizer and vocab
+    # objects as well as any special symbols we added to our dataset
+    train_dl, valid_dl, src_vocab, tgt_vocab, _, _, special_symbols = get_data(opts)
+
+    logging.info("Loaded data")
+
+    src_vocab_size = len(src_vocab)
+    tgt_vocab_size = len(tgt_vocab)
+
+    logging.info(f"{opts.src} vocab size: {src_vocab_size}")
+    logging.info(f"{opts.tgt} vocab size: {tgt_vocab_size}")
+
+    # Create model
+    model = Translator(
+        num_encoder_layers=opts.enc_layers,
+        num_decoder_layers=opts.dec_layers,
+        embed_size=opts.embed_size,
+        num_heads=opts.attn_heads,
+        src_vocab_size=src_vocab_size,
+        tgt_vocab_size=tgt_vocab_size,
+        dim_feedforward=opts.dim_feedforward,
+        dropout=opts.dropout
+    ).to(DEVICE)
+
+    logging.info("Model created... starting training!")
+
+    # Set up our learning tools
+    loss_fn = torch.nn.CrossEntropyLoss(ignore_index=special_symbols["<pad>"])
+
+    # These special values are from the "Attention is all you need" paper
+    optim = torch.optim.Adam(model.parameters(), lr=opts.lr, betas=(0.9, 0.98), eps=1e-9)
+
+    best_val_loss = 1e6
+
+    for idx, epoch in enumerate(range(1, opts.epochs+1)):
+
+        start_time = time()
+        train_loss = train(model, train_dl, loss_fn, optim, special_symbols, opts)
+        epoch_time = time() - start_time
+        val_loss   = validate(model, valid_dl, loss_fn, special_symbols)
+
+        # Once training is done, we want to save out the model
+        if val_loss < best_val_loss:
+            best_val_loss = val_loss
+            logging.info("New best model, saving...")
+            torch.save(model.state_dict(), opts.logging_dir + "best.pt")
+
+        torch.save(model.state_dict(), opts.logging_dir + "last.pt")
+
+        logger.info(f"Epoch: {epoch}\n\tTrain loss: {train_loss:.3f}\n\tVal loss: {val_loss:.3f}\n\tEpoch time = {epoch_time:.1f} seconds\n\tETA = {epoch_time*(opts.epochs-idx-1):.1f} seconds")
+
+if __name__ == "__main__":
+
+    parser = ArgumentParser(
+        prog="Machine Translator training and inference",
+    )
+
+    # Inference mode
+    parser.add_argument("--inference", action="store_true",
+                        help="Set true to run inference")
+    parser.add_argument("--model_path", type=str,
+                        help="Path to the model to run inference on")
+
+    # Translation settings
+    parser.add_argument("--src", type=str, default="de",
+                        help="Source language (translating FROM this language)")
+    parser.add_argument("--tgt", type=str, default="en",
+                        help="Target language (translating TO this language)")
+
+    # Training settings 
+    parser.add_argument("-e", "--epochs", type=int, default=30,
+                        help="Epochs")
+    parser.add_argument("--lr", type=float, default=1e-4,
+                        help="Default learning rate")
+    parser.add_argument("--batch", type=int, default=128,
+                        help="Batch size")
+    parser.add_argument("--backend", type=str, default="cpu",
+                        help="Batch size")
+
+    # Transformer settings
+    parser.add_argument("--attn_heads", type=int, default=8,
+                        help="Number of attention heads")
+    parser.add_argument("--enc_layers", type=int, default=5,
+                        help="Number of encoder layers")
+    parser.add_argument("--dec_layers", type=int, default=5,
+                        help="Number of decoder layers")
+    parser.add_argument("--embed_size", type=int, default=512,
+                        help="Size of the language embedding")
+    parser.add_argument("--dim_feedforward", type=int, default=512,
+                        help="Feedforward dimensionality")
+    parser.add_argument("--dropout", type=float, default=0.1,
+                        help="Transformer dropout")
+
+    # Logging settings
+    parser.add_argument("--logging_dir", type=str, default="./" + str(date.today()) + "/",
+                        help="Where the output of this program should be placed")
+
+    # Just for continuous integration
+    parser.add_argument("--dry_run", action="store_true")
+
+    args = parser.parse_args()
+
+    DEVICE = torch.device("cuda" if args.backend == "gpu" and torch.cuda.is_available() else "cpu")
+
+    if args.inference:
+        inference(args)
+    else:
+        main(args)

language_translation/requirements.txt

@@ -0,0 +1,5 @@
+torch
+torchtext
+torchdata
+spacy
+portalocker