Simple and Flexible API for training transformer models on sequence to sequence tasks.
pip install git+https://github.com/apoorvnandan/xformer.git
Have a simple interface built on top of pytorch and tensorflow for modelling any sequence to sequence problems with transformer models. The models have built in functions for training and generating outputs. (only with greedy decoding at the moment) And we have callbacks for use case specific customizations.
Check our minimal examples below!
Input:
- Case 1: Input is a sequence of token indices (shape: (batch_size,input_len), type: long)
- Case 2: Input is a sequence of feature vectors (shape: (batch_size,input_len,input_dim), type: float)
Output:
- Output is a sequence of token indices (shape: (batch_size,input_len), type: long)
This covers a lot of popular applications of sequence to sequence models:
- Machine Translation
- Abstractive Summarisation
- Automatic Speeech Recognition
- Video captioning
- Chatbots
We also provide built-in callbacks that help with the above use cases. You can also write a custom callback to execute your code at any point in the training loop.
Machine Translation: (with pytorch API)
from my_data import (
src_tokenizer,
trg_tokenizer,
train_loader,
test_loader
)
# data loader can be any iterable that returns the following:
print(next(iter(train_loader))) # {"enc_inp": <input batch (N,max_src_len,H)>, "dec_out": <target batch (N,max_trg_len)>}
from xformer import Transformer
from xformer.callbacks import BleuScore
model = Transformer.from_config(
num_classes=trg_tokenizer.size(),
embed_input=True,
input_vocab_size=src_tokenizer.size(),
src_pad_idx=src_tokenizer.pad_token_idx,
trg_pad_idx=trg_tokenizer.pad_token_idx
)
bleu_cb = BleuScore(
trg_tokenizer, test_loader, trg_tokenizer.bos_token_idx, trg_tokenizer.eos_token_idx
)
model.fit(train_loader, n_epochs=2, callbacks=[bleu_cb])Epoch 1/2
1070/1070 [==============================] - 279s 261ms/step - loss: 0.7809
test bleu score: 84.12
Epoch 2/2
1070/1070 [==============================] - 266s 248ms/step - loss: 0.1499
test bleu score: 88.49
Speech to text: (With tensorflow API)
from my_data import ds, val_ds
from xformer.tf import Transformer
from xformer.tf.callbacks import DisplayOutputs
# ds, val_ds are tf.data.Dataset objects which generate a batch like this
for i in ds.take(1):
print(i['src'].shape) # (4, 59, 80)
print(i['trg'].shape) # (4, 13)
model = Transformer(
input_type="feats",
nvocab=1000,
ninp=80,
nhid=64,
nhead=2,
nff=128,
src_maxlen=59,
trg_maxlen=12,
nlayers=2,
nclasses=30,
)
for i in val_ds.take(1):
batch = i # Use the first batch of validation set to display outputs
# vocabulary to convert preedicted indices to characters
idx_to_char = ["-"] + [chr(i + 96) for i in range(1, 27)] + ["<", ">", " "]
cb = DisplayOutputs(batch, idx_to_char)
model.compile(optimizer="adam")
model.fit(ds, callbacks=[cb], epochs=10)Epoch 1/15
475/475 [==============================] - 15s 22ms/step - loss: 0.5407
target: <one six>----
prediction: <four four>--
target: <six seven>--
prediction: <three three>
target: <seven three>
prediction: <three three>
target: <three nine>-
prediction: <five three>-
...
...
Epoch 15/15
475/475 [==============================] - 11s 23ms/step - loss: 0.0409
target: <one six>----
prediction: <one six>----
target: <six seven>--
prediction: <six seven>--
target: <seven three>
prediction: <seven three>
target: <three nine>-
prediction: <three nine>-
Heavily inspired by huggingface, keras and built on top of pytorch and tensorflow 2.x. The idea is to only write the necessary details about your model and data, and train a transformer model without any extra code. Callbacks provide an easy way to make the training code flexible.
All the models contain the entire architecture as a nn.Module or a keras.Model so that you can easily use them in other setups. (eg. using the encoder part to extract input representations and using them for a classification task)
The progress bars have been coded using tf.keras.utils.Progbar.
Callbacks allow you to execute your code at the following points in the training loop.
- Before the training loop starts - by overriding
on_train_start(self, model) - At the start of every epoch - by overriding
on_epoch_start(self, model) - At the end of every epoch - by overriding
on_epoch_end(self, model) - When the training ends - by overriding
on_fit_end(self, model)
For tensorflow, any custom Keras callback can be passed into the fit function.
For pytorch, simply extend the base xformer.callbacks.Callback class, and override the appropriate methods. Each of these methods have an argument: model. This argument contains the model object, so you can use it for everything you can use the original model object for.
Example: Callback for printing out the output of few inputs at the every epoch.
# Step 1: Extend base Callback class
from xformer.callbacks import Callback
class ExactMatchAccuracy(Callback):
# Step 2: Initialise with necessary objects to execute custom code
def __init__(self, input_batch, trg_tokenizer):
self.batch = input_batch
self.tokenizer = trg_tokenizer
# Step 3: Override appropriate method to execute your code in the training loop
# The argument 'model' is the transformer model object being trained.
def on_epoch_end(self, model):
model.model.eval() # model.model contains the `nn.Module`
enc_inp = self.batch['enc_inp']
dec_out = self.batch['dec_out']
bs = batch['enc_inp'].shape[0]
trg_bos_idx = self.tokenizer.trg_bos_idx
trg_eos_idx = self.tokenizer.trg_eos_idx
for i in range(bs):
preds,_ = model.generate(enc_inp[i,:], trg_bos_idx, trg_eos_idx)
pred_text = self.tokenizer.decode(preds)
target_text = self.tokenizer.decode(dec_out[i,:].numpy())
pad_token = self.tokenizer.idx_to_token[self.tokenizer.pad_token_idx]
target_text = target_text.replace(pad_token,'').strip() # remove pads
print('output:', pred_text)
print('target:', target_text)- Write minimum usable version with core functionality
- Test machine translation with small Eng-French dataset.
- Write API Reference
- Test speech to text
- Match notations between tf and pytorch modules
- Improve code quality and docstrings
- Put package on pip
- Multi GPU support
- Support for different schedulers and optimizers
- Upload some pretrained models
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