README.md

AutoScalingTensor

Automatic-resized PyTorch Tensor that supports all Pytorch API with almost zero abstraction cost. Amortized O(1) torch.cat along specific dimension.

Interface

Create an AutoScalingTensor

AutoScalingTensor(
    shape: tuple[int, ...],
    grow_on: int,
    init_tensor: torch.Tensor | None = None,
    init_val: int | float | None = None
)

• shape - the shape of tensor, all dimensions except the grow_on-dim will remain the same shape once created.
• grow_on - the dimension to append data on.
• init_tensor - (Optional) Use some existing tensor as the initial storage, init_tensor's shape must match shape argument.
• init_val - (Optional) The initial value for tensor. If not provided, tensor values will be uninitilized to maximize performance (using torch.empty). Otherwise, underlying tensor will always be initilized with init_val filled (using torch.fill).

Add data (efficiently) to AutoScalingTensor

AutoScalingTensor.push(x: torch.Tensor) -> None

• x - the shape should be the same as shape provided to __init__ except on grow_on-dim.

Retrieve data efficiently from AutoScalingTensor

acc: AutoScalingTensor  # Some AutoScalingTensor

acc_tensor_view: torch.Tensor = acc.tensor      # Get a view of all data with *.tensor
acc_partial_view: torch.Tensor = acc[..., :100] # All indexing methods are supported, advanced or naive.

Efficient Tensor Accumulation

Concatenating 1 x 3 tensor into an accumulator tensor iteratively for 400,000 iterations, AutoScalingTensor only need <2sec while naive torch.Tensor need 35sec+ on Apple M2 chip laptop.

Num_iter	Time (AutoScalingTensor)	Time (torch.Tensor)
200,000	0.9995s	8.621s
300,000	1.4492s	21.6432s
400,000	1.8861s	37.9394s

Benchmarking Code:

@timing
def test_autoscale(niter: int) -> AutoScalingTensor:
    accumulator = AutoScalingTensor(shape=(8, 3), grow_on=0)
    data = torch.tensor([[1, 2, 3]])
    for idx in range(niter):
        accumulator.push(data * idx)
    return accumulator

@timing
def test_naive_cat(niter: int) -> torch.Tensor:
    accumulator = torch.zeros((0, 3))
    data = torch.tensor([[1, 2, 3]])
    for idx in range(niter):
        accumulator = torch.cat([accumulator, data * idx], dim=0)
    return accumulator

A = test_autoscale(200000)
B = test_naive_cat(200000)

Fully Compatible with torch.Tensor

AutoScalingTensor can merge into existing PyTorch projects with ZERO COST. AutoScalingTensor supports all PyTorch APIs, chain-calling, advanced indexing, etc. just like a torch.Tensor do.

>>> from AutoScaleTensor import AutoScalingTensor
>>> import torch
>>> A = AutoScalingTensor((1, 3), grow_on=0)
>>> A.push(torch.tensor([[0., 0., 0.], [10., 20., 30.]]))
>>> A
AutoScalingTensor(alloc=4, actual=2, 
        data=tensor([[ 0.,  0.,  0.],
        [10., 20., 30.]])
)
>>> A[0]
tensor([0., 0., 0.])
>>> A[0] = 3.
>>> A
AutoScalingTensor(alloc=4, actual=2, 
        data=tensor([[ 3.,  3.,  3.],
        [10., 20., 30.]])
)
>>> A[1].mean()
tensor(20.)