## TfPyTh

Putting TensorFlow back in PyTorch, back in TensorFlow (with differentiable TensorFlow PyTorch adapters).

Do you have a codebase that uses TensorFlow and one that uses PyTorch and want to train a model that uses both end-to-end?

This library makes it possible without having to rewrite either codebase!

It allows you to wrap a TensorFlow graph to make it callable (and differentiable) through PyTorch, and vice-versa, using simple functions.

The only caveat is that tensors have to be copied and routed through the CPU until TensorFlow supports `__cuda_array_interface`

(please star the GitHub issue).

## Install

```
pip install tfpyth
```

### Example

```
import tensorflow as tf
import torch as th
import numpy as np
import tfpyth
session = tf.Session()
def get_torch_function():
a = tf.placeholder(tf.float32, name='a')
b = tf.placeholder(tf.float32, name='b')
c = 3 * a + 4 * b * b
f = tfpyth.torch_from_tensorflow(session, [a, b], c).apply
return f
f = get_torch_function()
a = th.tensor(1, dtype=th.float32, requires_grad=True)
b = th.tensor(3, dtype=th.float32, requires_grad=True)
x = f(a, b)
assert x == 39.
x.backward()
assert np.allclose((a.grad, b.grad), (3., 24.))
```

## What it's got

`torch_from_tensorflow`

Creates a PyTorch function that is differentiable by evaluating a TensorFlow output tensor given input placeholders.

`eager_tensorflow_from_torch`

Creates an eager Tensorflow function from a PyTorch function.

`tensorflow_from_torch`

Creates a TensorFlow op/tensor from a PyTorch function.

## Future work

- support JAX
- support higher-order derivatives