pytorch-widedeep
A flexible package to combine tabular data with text and images using wide and deep models.
Introduction
pytorch-widedeep
is based on Google's Wide and Deep Algorithm. Details of
the original algorithm can be found
here, and the nice
research paper can be found here.
In general terms, pytorch-widedeep
is a package to use deep learning with
tabular data. In particular, is intended to facilitate the combination of text
and images with corresponding tabular data using wide and deep models. With
that in mind there are two architectures that can be implemented with just a
few lines of code.
Architectures
Architecture 1:
Architecture 1 combines the Wide
, one-hot encoded features with the outputs
from the DeepDense
, DeepText
and DeepImage
components connected to a
final output neuron or neurons, depending on whether we are performing a
binary classification or regression, or a multi-class classification. The
components within the faded-pink rectangles are concatenated.
In math terms, and following the notation in the paper, Architecture 1 can be formulated as:
Where 'W' are the weight matrices applied to the wide model and to the final activations of the deep models, 'a' are these final activations, and φ(x) are the cross product transformations of the original features 'x'. In case you are wondering what are "cross product transformations", here is a quote taken directly from the paper: "For binary features, a cross-product transformation (e.g., “AND(gender=female, language=en)”) is 1 if and only if the constituent features (“gender=female” and “language=en”) are all 1, and 0 otherwise".
Architecture 2
Architecture 2 combines the Wide
one-hot encoded features with the Deep
components of the model connected to the output neuron(s), after the different
Deep components have been themselves combined through a FC-Head (that I refer
as deephead
).
In math terms, and following the notation in the paper, Architecture 2 can be formulated as:
When using pytorch-widedeep
, the assumption is that the so called Wide
and
DeepDense
components in the figures are always present, while DeepText
and DeepImage
are optional. pytorch-widedeep
includes standard text (stack
of LSTMs) and image (pre-trained ResNets or stack of CNNs) models. However,
the user can use any custom model as long as it has an attribute called
output_dim
with the size of the last layer of activations, so that
WideDeep
can be constructed. See the examples folder for more information.
Installation
Install using pip:
pip install pytorch-widedeep
Or install directly from github
pip install git+https://github.com/jrzaurin/pytorch-widedeep.git
Developer Install
# Clone the repository
git clone https://github.com/jrzaurin/pytorch-widedeep
cd pytorch-widedeep
# Install in dev mode
pip install -e .
Examples
There are a number of notebooks in the examples
folder plus some additional
files. These notebooks cover most of the utilities of this package and can
also act as documentation. In the case that github does not render the
notebooks, or it renders them missing some parts, they are saved as markdown
files in the docs
folder.
Quick start
Binary classification with the adult
dataset
using Wide
and DeepDense
and defaults settings.
import pandas as pd
from pytorch_widedeep.preprocessing import WidePreprocessor, DeepPreprocessor
from pytorch_widedeep.models import Wide, DeepDense, WideDeep
from pytorch_widedeep.metrics import BinaryAccuracy
# these next 3 lines are not directly related to pytorch-widedeep. I assume
# you have downloaded the dataset and place it in a dir called data/adult/
df = pd.read_csv('data/adult/adult.csv.zip')
df['income_label'] = (df["income"].apply(lambda x: ">50K" in x)).astype(int)
df.drop('income', axis=1, inplace=True)
# prepare wide, crossed, embedding and continuous columns
wide_cols = ['education', 'relationship', 'workclass', 'occupation','native-country', 'gender']
cross_cols = [('education', 'occupation'), ('native-country', 'occupation')]
embed_cols = [('education',16), ('workclass',16), ('occupation',16),('native-country',32)]
cont_cols = ["age", "hours-per-week"]
target_col = 'income_label'
# target
target = df[target_col].values
# wide
preprocess_wide = WidePreprocessor(wide_cols=wide_cols, crossed_cols=cross_cols)
X_wide = preprocess_wide.fit_transform(df)
wide = Wide(wide_dim=X_wide.shape[1], output_dim=1)
# deepdense
preprocess_deep = DeepPreprocessor(embed_cols=embed_cols, continuous_cols=cont_cols)
X_deep = preprocess_deep.fit_transform(df)
deepdense = DeepDense(hidden_layers=[64,32],
deep_column_idx=preprocess_deep.deep_column_idx,
embed_input=preprocess_deep.embeddings_input,
continuous_cols=cont_cols)
# build, compile, fit and predict
model = WideDeep(wide=wide, deepdense=deepdense)
model.compile(method='binary', metrics=[BinaryAccuracy])
model.fit(X_wide=X_wide, X_deep=X_deep, target=target, n_epochs=5, batch_size=256, val_split=0.2)
model.predict(X_wide=X_wide_te, X_deep=X_deep_te)
Of course, one can do much more, such as using different initializations,
optimizers or learning rate schedulers for each component of the overall
model. Adding FC-Heads to the Text and Image components. Using the Focal
Loss, warming up individual components
before joined training, etc. See the examples
or the docs
folders for a
better understanding of the content of the package and its functionalities.
Testing
pytest tests
Acknowledgments
This library takes from a series of other libraries, so I think it is just fair to mention them here in the README (specific mentions are also included in the code).
The Callbacks
and Initializers
structure and code is inspired by the
torchsample
library, which in
itself partially inspired by Keras
.
The TextProcessor
class in this library uses the
fastai
's
Tokenizer
and Vocab
. The code at utils.fastai_transforms
is a minor
adaptation of their code so it functions within this library. To my experience
their Tokenizer
is the best in class.
The ImageProcessor
class in this library uses code from the fantastic Deep
Learning for Computer
Vision
(DL4CV) book by Adrian Rosebrock.