oneflow.nn.Unfold

class oneflow.nn.Unfold(kernel_size: Union[int, Tuple[int, int]], dilation: Union[int, Tuple[int, int]] = 1, padding: Union[int, Tuple[int, int]] = 0, stride: Union[int, Tuple[int, int]] = 1)

This op extracts elements in a local window from input tensor, it also called img2col.

Consider a batched input tensor of shape \((N, C, *)\), where \(N\) is the batch dimension, \(C\) is the channel dimension, and \(*\) represent arbitrary spatial dimensions. This operation flattens each sliding kernel_size-sized block within the spatial dimensions of input into a column (i.e., last dimension) of a 3-D output tensor of shape \((N, C \times \prod(\text{kernel\_size}), L)\), where \(C \times \prod(\text{kernel\_size})\) is the total number of values within each block (a block has \(\prod(\text{kernel\_size})\) spatial locations each containing a \(C\)-channeled vector), and \(L\) is the total number of such blocks:

\[L = \prod_d \left\lfloor\frac{\text{spatial\_size}[d] + 2 \times \text{padding}[d] % - \text{dilation}[d] \times (\text{kernel\_size}[d] - 1) - 1}{\text{stride}[d]} + 1\right\rfloor,\]

where \(\text{spatial\_size}\) is formed by the spatial dimensions of input (\(*\) above), and \(d\) is over all spatial dimensions.

Therefore, indexing output at the last dimension (column dimension) gives all values within a certain block.

Parameters

• kernel_size (_size_2_t) – The size of kernel.

• dilation (_size_2_t, optional) – The dilation rate. Defaults to 1.

• padding (_size_2_t, optional) – The padding value. Defaults to 0.

• stride (_size_2_t, optional) – The stride of sliding window. Defaults to 1.

For example:

>>> import oneflow as flow
>>> import numpy as np

>>> x_tensor = flow.Tensor(np.random.randn(1, 1, 4, 4))
>>> unfold = flow.nn.Unfold(kernel_size=3, padding=1)
>>> out = unfold(x_tensor)
>>> out.shape
oneflow.Size([1, 9, 16])

__init__(kernel_size: Union[int, Tuple[int, int]], dilation: Union[int, Tuple[int, int]] = 1, padding: Union[int, Tuple[int, int]] = 0, stride: Union[int, Tuple[int, int]] = 1) → None

Initialize self. See help(type(self)) for accurate signature.

Methods

__call__(*args, **kwargs)	Call self as a function.
__delattr__(name, /)	Implement delattr(self, name).
__dir__()	Default dir() implementation.
__eq__(value, /)	Return self==value.
__format__(format_spec, /)	Default object formatter.
__ge__(value, /)	Return self>=value.
__getattr__(name)
__getattribute__(name, /)	Return getattr(self, name).
__gt__(value, /)	Return self>value.
__hash__()	Return hash(self).
__init__(kernel_size[, dilation, padding, …])	Initialize self.
__init_subclass__	This method is called when a class is subclassed.
__le__(value, /)	Return self<=value.
__lt__(value, /)	Return self<value.
__ne__(value, /)	Return self!=value.
__new__(**kwargs)	Create and return a new object.
__reduce__()	Helper for pickle.
__reduce_ex__(protocol, /)	Helper for pickle.
__repr__()	Return repr(self).
__setattr__(name, value)	Implement setattr(self, name, value).
__sizeof__()	Size of object in memory, in bytes.
__str__()	Return str(self).
__subclasshook__	Abstract classes can override this to customize issubclass().
_apply(fn[, applied_dict])
_get_name()
_load_from_state_dict(state_dict, prefix, …)
_named_members(get_members_fn[, prefix, recurse])
_save_to_state_dict(destination, prefix, …)
_shallow_repr()
add_module(name, module)	Adds a child module to the current module.
apply(fn)	Applies fn recursively to every submodule (as returned by .children()) as well as self.
buffers([recurse])	Returns an iterator over module buffers.
children()	Returns an iterator over immediate children modules.
cpu()	Moves all model parameters and buffers to the CPU.
cuda([device])	Moves all model parameters and buffers to the GPU.
double()	Casts all floating point parameters and buffers to double datatype.
eval()	Sets the module in evaluation mode.
extra_repr()	Set the extra representation of the module
float()	Casts all floating point parameters and buffers to float datatype.
forward(input)
half()	Casts all floating point parameters and buffers to half datatype.
load_state_dict(state_dict[, strict])	Copies parameters and buffers from state_dict into this module and its descendants.
modules()	Returns an iterator over all modules in the network.
named_buffers([prefix, recurse])	Returns an iterator over module buffers, yielding both the name of the buffer as well as the buffer itself.
named_children()	Returns an iterator over immediate children modules, yielding both the name of the module as well as the module itself.
named_modules([memo, prefix])	Returns an iterator over all modules in the network, yielding both the name of the module as well as the module itself.
named_parameters([prefix, recurse])	Returns an iterator over module parameters, yielding both the name of the parameter as well as the parameter itself.
parameters([recurse])	Returns an iterator over module parameters.
register_buffer(name, tensor[, persistent])	Adds a buffer to the module.
register_forward_hook(hook)	Registers a forward hook on the module.
register_forward_pre_hook(hook)	Registers a forward pre-hook on the module.
register_parameter(name, param)	Adds a parameter to the module.
state_dict([destination, prefix, keep_vars])	Returns a dictionary containing a whole state of the module.
to([device])	Moves the parameters and buffers.
to_consistent(*args, **kwargs)	This interface is no longer available, please use oneflow.nn.Module.to_global() instead.
to_global([placement, sbp])	Convert the parameters and buffers to global.
train([mode])	Sets the module in training mode.
zero_grad([set_to_none])	Sets gradients of all model parameters to zero.