einops.reduce
einops.reduce provides combination of reordering and reduction using reader-friendly notation.
Examples for reduce operation:
>>> x = np.random.randn(100, 32, 64)
# perform max-reduction on the first axis
>>> y = reduce(x, 't b c -> b c', 'max')
# same as previous, but with clearer axes meaning
>>> y = reduce(x, 'time batch channel -> batch channel', 'max')
>>> x = np.random.randn(10, 20, 30, 40)
# 2d max-pooling with kernel size = 2 * 2 for image processing
>>> y1 = reduce(x, 'b c (h1 h2) (w1 w2) -> b c h1 w1', 'max', h2=2, w2=2)
# if one wants to go back to the original height and width, depth-to-space trick can be applied
>>> y2 = rearrange(y1, 'b (c h2 w2) h1 w1 -> b c (h1 h2) (w1 w2)', h2=2, w2=2)
>>> assert parse_shape(x, 'b _ h w') == parse_shape(y2, 'b _ h w')
# Adaptive 2d max-pooling to 3 * 4 grid
>>> reduce(x, 'b c (h1 h2) (w1 w2) -> b c h1 w1', 'max', h1=3, w1=4).shape
(10, 20, 3, 4)
# Global average pooling
>>> reduce(x, 'b c h w -> b c', 'mean').shape
(10, 20)
# Subtracting mean over batch for each channel
>>> y = x - reduce(x, 'b c h w -> () c () ()', 'mean')
# Subtracting per-image mean for each channel
>>> y = x - reduce(x, 'b c h w -> b c () ()', 'mean')
Parameters:
Name | Type | Description | Default |
---|---|---|---|
tensor |
Union[Tensor, List[Tensor]]
|
tensor: tensor of any supported library (e.g. numpy.ndarray, tensorflow, pytorch). list of tensors is also accepted, those should be of the same type and shape |
required |
pattern |
str
|
string, reduction pattern |
required |
reduction |
Reduction
|
one of available reductions ('min', 'max', 'sum', 'mean', 'prod'), case-sensitive alternatively, a callable f(tensor, reduced_axes) -> tensor can be provided. This allows using various reductions, examples: np.max, tf.reduce_logsumexp, torch.var, etc. |
required |
axes_lengths |
Size
|
any additional specifications for dimensions |
{}
|
Returns:
Type | Description |
---|---|
Tensor
|
tensor of the same type as input |
Source code in einops/einops.py
460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 |
|