Authors: Alexander Holden Miller, Margaret Li
First, make sure you have Python 3. Now open up terminal and run the following.
Clone ParlAI Repository:
git clone https://github.com/facebookresearch/ParlAI.git ~/ParlAI
cd ~/ParlAI; python setup.py develop
Several models have additional requirements, such as PyTorch.
View a task & train a model¶
Let’s start by printing out the first few examples of the bAbI tasks, task 1.
# display examples from bAbI 10k task 1 python python -m parlai.scripts.display_data -t babi:task10k:1
Now let’s try to train a model on it (even on your laptop, this should train fast).
# train MemNN using batch size 1 and 4 threads for 5 epochs python python -m parlai.scripts.train_model -t babi:task10k:1 -mf /tmp/babi_memnn -bs 1 -nt 4 -eps 5 -m memnn --no-cuda
Let’s print some of its predictions to make sure it’s working.
# display predictions for model save at specified file on bAbI task 1 python python -m parlai.scripts.display_model -t babi:task10k:1 -mf /tmp/babi_memnn -ecands vocab
The “eval_labels” and “MemNN” lines should (usually) match!
Let’s try asking the model a question ourselves.
# interact with saved model python python -m parlai.scripts.interactive -mf /tmp/babi_memnn -ecands vocab ... Enter your message: John went to the hallway.\n Where is John?
Hopefully the model gets this right!
Train a Transformer on Twitter¶
Now let’s try training a Transformer (Vaswani, et al 2017) ranker model. Make sure to complete this section on a GPU with PyTorch installed.
We’ll be training on the Twitter task, which is a dataset of tweets and replies.
There’s more information on tasks in these docs,
including a full list of tasks and
on specifying arguments for training and evaluation (like the
-t <task> argument used here).
Let’s begin again by printing the first few examples.
# display first examples from twitter dataset python python -m parlai.scripts.display_data -t twitter
Now, we’ll train the model. This will take a while to reach convergence.
# train transformer ranker python python -m parlai.scripts.train_model -t twitter -mf /tmp/tr_twitter -m transformer/ranker -bs 16 -vtim 3600 -cands batch -ecands batch --data-parallel True
You can modify some of the command line arguments we use here - we set batch size to 10, run validation every 3600 seconds, and take candidates from the batch for training and evaluation.
The train model script will by default save the model after achieving best validation results so far.
The Twitter task is quite large, and validation is run by default after each epoch (full pass through the train data),
but we want to save our model more frequently so we set validation to run once an hour with
This train model script evaluates the model on the valid and test sets at the end of training, but if we wanted to evaluate a saved model - perhaps to compare the results of our newly trained Transformer against the BlenderBot 90M baseline from our Model Zoo, we could do the following:
# Evaluate the tiny BlenderBot model on twitter data python examples/eval_model.py -t twitter -mf zoo:blender/blender_90M/model
Finally, let’s print some of our transformer’s predictions with the same display_model script from above.
# display predictions for model saved at specific file on twitter python python -m parlai.scripts.display_model -t twitter -mf /tmp/tr_twitter -ecands batch
Add a simple model¶
Let’s put together a super simple model which will print the parsed version of what is said to it.
First let’s set it up.
mkdir parlai/agents/parrot touch parlai/agents/parrot/parrot.py
We’ll inherit the TorchAgent parsing code so we don’t have to write it ourselves. Open parrot.py and copy the following:
from parlai.core.torch_agent import TorchAgent, Output class ParrotAgent(TorchAgent): def train_step(self, batch): pass def eval_step(self, batch): # for each row in batch, convert tensor to back to text strings return Output([self.dict.vec2txt(row) for row in batch.text_vec]) def build_model(self, batch): # Our agent doesn't have a real model, so we will return a placeholder # here. return None
Now let’s test it out:
python python -m parlai.scripts.display_model -t babi:task10k:1 -m parrot
You’ll notice the model is always outputting the “unknown” token. This token is automatically selected because the dictionary doesn’t recognize any tokens, because we haven’t built a dictionary yet. Let’s do that now.
python python -m parlai.scripts.build_dict -t babi:task10k:1 -df /tmp/parrot.dict
Now let’s try our Parrot agent again.
python python -m parlai.scripts.display_model -t babi:task10k:1 -m parrot -df /tmp/parrot.dict
This ParrotAgent implements
eval_step, one of two abstract functions in TorchAgent.
The other is
You can easily and quickly build a model agent by creating a class which implements only these two functions with the most
typical custom code for a model, and inheriting vectorization and batching from TorchAgent.
As needed, you can also override any functions to change the default argument values or to override the behavior with your own. For example, you could change the vectorizer to return numpy arrays instead of Torch Tensors.
To see more details about ParlAI’s general structure, how tasks and models are set up, or how to use Mechanical Turk, Messenger, Tensorboard, and more – check out the other tutorials.