patrick-kidger / torchtyping

Type annotations and dynamic checking for a tensor's shape, dtype, names, etc.
Apache License 2.0
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named-tensors python-typing pytorch shape tensors typing

torchtyping

Type annotations for a tensor's shape, dtype, names, ...

Welcome! For new projects I now strongly recommend using my newer jaxtyping project instead. It supports PyTorch, doesn't actually depend on JAX, and unlike TorchTyping it is compatible with static type checkers. :)


Turn this:

def batch_outer_product(x: torch.Tensor, y: torch.Tensor) -> torch.Tensor:
    # x has shape (batch, x_channels)
    # y has shape (batch, y_channels)
    # return has shape (batch, x_channels, y_channels)

    return x.unsqueeze(-1) * y.unsqueeze(-2)

into this:

def batch_outer_product(x:   TensorType["batch", "x_channels"],
                        y:   TensorType["batch", "y_channels"]
                        ) -> TensorType["batch", "x_channels", "y_channels"]:

    return x.unsqueeze(-1) * y.unsqueeze(-2)

with programmatic checking that the shape (dtype, ...) specification is met.

Bye-bye bugs! Say hello to enforced, clear documentation of your code.

If (like me) you find yourself littering your code with comments like # x has shape (batch, hidden_state) or statements like assert x.shape == y.shape , just to keep track of what shape everything is, then this is for you.


Installation

pip install torchtyping

Requires Python >=3.7 and PyTorch >=1.7.0.

If using typeguard then it must be a version <3.0.0.

Usage

torchtyping allows for type annotating:

If typeguard is (optionally) installed then at runtime the types can be checked to ensure that the tensors really are of the advertised shape, dtype, etc.

# EXAMPLE

from torch import rand
from torchtyping import TensorType, patch_typeguard
from typeguard import typechecked

patch_typeguard()  # use before @typechecked

@typechecked
def func(x: TensorType["batch"],
         y: TensorType["batch"]) -> TensorType["batch"]:
    return x + y

func(rand(3), rand(3))  # works
func(rand(3), rand(1))
# TypeError: Dimension 'batch' of inconsistent size. Got both 1 and 3.

typeguard also has an import hook that can be used to automatically test an entire module, without needing to manually add @typeguard.typechecked decorators.

If you're not using typeguard then torchtyping.patch_typeguard() can be omitted altogether, and torchtyping just used for documentation purposes. If you're not already using typeguard for your regular Python programming, then strongly consider using it. It's a great way to squash bugs. Both typeguard and torchtyping also integrate with pytest, so if you're concerned about any performance penalty then they can be enabled during tests only.

API

torchtyping.TensorType[shape, dtype, layout, details]

The core of the library.

Each of shape, dtype, layout, details are optional.

torchtyping.patch_typeguard()

torchtyping integrates with typeguard to perform runtime type checking. torchtyping.patch_typeguard() should be called at the global level, and will patch typeguard to check TensorTypes.

This function is safe to run multiple times. (It does nothing after the first run).

pytest --torchtyping-patch-typeguard

torchtyping offers a pytest plugin to automatically run torchtyping.patch_typeguard() before your tests. pytest will automatically discover the plugin, you just need to pass the --torchtyping-patch-typeguard flag to enable it. Packages can then be passed to typeguard as normal, either by using @typeguard.typechecked, typeguard's import hook, or the pytest flag --typeguard-packages="your_package_here".

Further documentation

See the further documentation for: