functorch.make_functional

functorch.make_functional(model, disable_autograd_tracking=False) → func, params

Given a torch.nn.Module, make_functional() extracts the state (params) and returns a functional version of the model, func. This makes it so that it is possible use transforms over the parameters of model.

func can be invoked as follows:

import torch
import torch.nn as nn
from functorch import make_functional

x = torch.randn(4, 3)
model = nn.Linear(3, 3)
func, params = make_functional(model)
func(params, x)

And here is an example of applying the grad transform over the parameters of a model.

import torch
import torch.nn as nn
from functorch import make_functional, grad

x = torch.randn(4, 3)
t = torch.randn(4, 3)
model = nn.Linear(3, 3)
func, params = make_functional(model)

def compute_loss(params, x, t):
    y = func(params, x)
    return nn.functional.mse_loss(y, t)

grad_weights = grad(compute_loss)(params, x, t)

If the model has any buffers, please use make_functional_with_buffers() instead.

Parameters

• model (torch.nn.Module) – Input model.

• disable_autograd_tracking (bool) – Flag to disable gradients tracking for output parameters. The returned params are unrelated to the set of params from the original model. If False (default), the params will have requires_grad=True on them (aka they will be trackable with regular PyTorch autograd), matching the requires_grad-ness of the params from the original model. Otherwise, the returned params will have requires_grad=False. Default, False. If you plan on using regular PyTorch autograd (e.g., if you want to call .backward() or torch.autograd.grad(), then set disable_autograd_tracking=False. Otherwise, if you’re only planning on using functorch’s gradient transforms, then please set disable_autograd_tracking=True to avoid unnecessarily tracking history with PyTorch autograd.

Warning

We’ve integrated functorch into PyTorch. As the final step of the integration, functorch.make_functional is deprecated as of PyTorch 2.0 and will be deleted in a future version of PyTorch >= 2.3. Please use torch.func.functional_call instead; see the PyTorch 2.0 release notes and/or the torch.func migration guide for more details https://pytorch.org/docs/main/func.migrating.html