TensorFlow vs PyTorch vs Keras for NLP

By Kevin Vu, Exxact Corp.

Before beginning a feature comparison between TensorFlow vs PyTorch vs Keras, let’s cover some soft, non-competitive differences between them.

Below we present some differences between the three that should serve as an introduction to TensorFlow vs PyTorch vs Keras.

These differences aren’t written in the spirit of comparing one with the other but with a spirit of introducing the subject of our discussion in this article.

TensorFlowPyTorchKeras Now let’s bring more competitive facts about the three of them.

We are specifically looking to do a comparative analysis of the frameworks focusing on Natural Language Processing.

1.

Types of RNNs available in bothWhen looking for a Deep Learning solution to an NLP problem, Recurrent Neural Networks (RNNs) are the most popular go-to architecture for the developers.

Therefore, it makes sense to compare the frameworks from this perspective.

All of the frameworks under consideration, have modules that allow us to create simple RNNs as well as their more evolved variants — Gated Recurrent Units (GRU) and Long Short Term Memory (LSTM) networks.

PyTorch:PyTorch provides 2 levels of classes for building such recurrent networks:So, the multi-layer classes are like a nice wrapper to the cell-level classes for the time when we don’t want much customization within our neural network.

Also, making an RNN bi-direction is as simple as setting the bidirectional argument to True in the multi-layer classes!Check out our article — Getting Started with NLP using the PyTorch framework — to dive into more details on these classes.

TensorFlow:TensorFlow provides us with a tf.

nn.

rnn_cell module to help us with our standard RNN needs.

Some of the most important classes in the tf.

nn.

rnn_cell module are as follows:Check out our article — Getting Started with NLP using the TensorFlow and Keras framework — to dive into more details of this module.

Keras:Below are the recurrent layers provided in the Keras library.

These layers include:Check out our article — Getting Started with NLP using the TensorFlow and Keras framework — to dive into more details on these classes.

All three of TensorFlow, PyTorch, and Keras have built-in capabilities to allow us to create popular RNN architectures.

The difference lies in their interface.

Keras has a simple interface with a small list of well-defined parameters, makes the above classes easy to implement.

Being a high-level API on top of TensorFlow, we can say that Keras makes TensorFlow easy.

While PyTorch provides a similar level of flexibility as TensorFlow, it has a much cleaner interface.

While we are on the subject, let’s dive deeper into a comparative study based on the ease of use for each framework.

2.

Ease of use TensorFlow vs PyTorch vs KerasTensorFlow is often reprimanded over its incomprehensive API.

PyTorch is way more friendly and simpler to use.

Overall, the PyTorch framework is more tightly integrated with Python language and feels more native most of the times.

When you write in TensorFlow sometimes you feel that your model is behind a brick wall with several tiny holes to communicate over.

And that’s why, Keras.

Let’s discuss a few more factors comparing the three, based on their ease of use:Static computational graphs vs dynamic computational graphs:This factor is especially important in NLP.

TensorFlow uses static graphs for computation, while PyTorch uses dynamic computation graphs.

This means that in Tensorflow, you define the computation graph statically before a model is run.

All communication with outer world is performed via tf.

Session object and tf.

Placeholder which are tensors that will be substituted by external data at runtime.

In PyTorch things are way more imperative and dynamic: you can define, change, and execute nodes as you go, no special session interfaces or placeholders.

In RNNs, with static graphs, the input sequence length will stay constant.

This means that if you develop a sentiment analysis model for English sentences, you must fix the sentence length to some maximum value and pad all smaller sequences with zeros.

Not too convenient, right?Debugging:Since computation graph in PyTorch is defined at runtime you can use our favorite Python debugging tools such as pdb, ipdb, PyCharm debugger or old trusty print statements.

This is not the case with TensorFlow.

You have an option to use a special tool called tfdbg,  which allows to evaluate TensorFlow expressions at runtime and browse all tensors and operations in session scope.

Of course, you won’t be able to debug any python code with it, so it will be necessary to use pdb separately.

Tensorflow is more mature than PyTorch.

It has a much larger community as compared to PyTorch and Keras combined.

Its user base is growing faster than both PyTorch and Keras.

So this means —Future of NLP:While Recurrent Neural Networks have been the “go-to” architecture for NLP tasks for a while now, its probably not going to be this way forever.

We already have a newer Transformer model, based on the Attention mechanism, gaining popularity amongst the researchers.

It is already being hailed as the new NLP standard, replacing Recurrent Neural Networks.

Some commentators believe that the Transformer will become the dominant NLP deep learning architecture of 2019.

Check out our comprehensive 3-part tutorial to get started with Transformers.

Tensorflow seems to be ahead in this race:This is not to say that PyTorch is far behind, many pre-trained transformer models are available at Huggingface’s https://github.

com/huggingface/pytorch-transformers.

So, that’s all about the comparison.

But before parting ways, let me tell you about something that might make this whole conversation obsolete in one year!Google recently announced Tensorflow 2.

0,  and it is a game-changer!Here’s how:So, that mitigates almost all the complains that people have about TensorFlow, I guess, which means that TensorFlow will consolidate its position as the go-to framework for all deep learning tasks, even better now!Original.

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