207 lines
8.3 KiB
Python
207 lines
8.3 KiB
Python
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# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Private utilities for locally-connected layers."""
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import numpy as np
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import tensorflow.compat.v2 as tf
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from keras import backend
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from keras.utils import conv_utils
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def get_locallyconnected_mask(
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input_shape, kernel_shape, strides, padding, data_format
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):
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"""Return a mask representing connectivity of a locally-connected operation.
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This method returns a masking numpy array of 0s and 1s (of type
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`np.float32`) that, when element-wise multiplied with a fully-connected
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weight tensor, masks out the weights between disconnected input-output pairs
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and thus implements local connectivity through a sparse fully-connected
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weight tensor.
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Assume an unshared convolution with given parameters is applied to an input
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having N spatial dimensions with `input_shape = (d_in1, ..., d_inN)`
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to produce an output with spatial shape `(d_out1, ..., d_outN)` (determined
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by layer parameters such as `strides`).
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This method returns a mask which can be broadcast-multiplied (element-wise)
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with a 2*(N+1)-D weight matrix (equivalent to a fully-connected layer
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between (N+1)-D activations (N spatial + 1 channel dimensions for input and
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output) to make it perform an unshared convolution with given
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`kernel_shape`, `strides`, `padding` and `data_format`.
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Args:
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input_shape: tuple of size N: `(d_in1, ..., d_inN)` spatial shape of the
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input.
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kernel_shape: tuple of size N, spatial shape of the convolutional kernel /
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receptive field.
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strides: tuple of size N, strides along each spatial dimension.
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padding: type of padding, string `"same"` or `"valid"`.
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data_format: a string, `"channels_first"` or `"channels_last"`.
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Returns:
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a `np.float32`-type `np.ndarray` of shape
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`(1, d_in1, ..., d_inN, 1, d_out1, ..., d_outN)`
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if `data_format == `"channels_first"`, or
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`(d_in1, ..., d_inN, 1, d_out1, ..., d_outN, 1)`
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if `data_format == "channels_last"`.
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Raises:
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ValueError: if `data_format` is neither `"channels_first"` nor
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`"channels_last"`.
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"""
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mask = conv_utils.conv_kernel_mask(
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input_shape=input_shape,
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kernel_shape=kernel_shape,
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strides=strides,
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padding=padding,
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)
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ndims = int(mask.ndim / 2)
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if data_format == "channels_first":
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mask = np.expand_dims(mask, 0)
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mask = np.expand_dims(mask, -ndims - 1)
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elif data_format == "channels_last":
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mask = np.expand_dims(mask, ndims)
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mask = np.expand_dims(mask, -1)
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else:
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raise ValueError("Unrecognized data_format: " + str(data_format))
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return mask
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def local_conv_matmul(inputs, kernel, kernel_mask, output_shape):
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"""Apply N-D convolution with un-shared weights using a single matmul call.
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This method outputs `inputs . (kernel * kernel_mask)`
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(with `.` standing for matrix-multiply and `*` for element-wise multiply)
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and requires a precomputed `kernel_mask` to zero-out weights in `kernel` and
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hence perform the same operation as a convolution with un-shared
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(the remaining entries in `kernel`) weights. It also does the necessary
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reshapes to make `inputs` and `kernel` 2-D and `output` (N+2)-D.
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Args:
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inputs: (N+2)-D tensor with shape `(batch_size, channels_in, d_in1, ...,
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d_inN)` or `(batch_size, d_in1, ..., d_inN, channels_in)`.
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kernel: the unshared weights for N-D convolution,
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an (N+2)-D tensor of shape: `(d_in1, ..., d_inN, channels_in,
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d_out2, ..., d_outN, channels_out)` or `(channels_in, d_in1, ...,
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d_inN, channels_out, d_out2, ..., d_outN)`, with the ordering of
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channels and spatial dimensions matching that of the input. Each
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entry is the weight between a particular input and output location,
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similarly to a fully-connected weight matrix.
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kernel_mask: a float 0/1 mask tensor of shape: `(d_in1, ..., d_inN, 1,
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d_out2, ..., d_outN, 1)` or `(1, d_in1, ..., d_inN, 1, d_out2, ...,
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d_outN)`, with the ordering of singleton and spatial dimensions
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matching that of the input. Mask represents the connectivity pattern
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of the layer and is precomputed elsewhere based on layer parameters:
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stride, padding, and the receptive field shape.
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output_shape: a tuple of (N+2) elements representing the output shape:
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`(batch_size, channels_out, d_out1, ..., d_outN)` or `(batch_size,
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d_out1, ..., d_outN, channels_out)`, with the ordering of channels and
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spatial dimensions matching that of the input.
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Returns:
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Output (N+2)-D tensor with shape `output_shape`.
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"""
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inputs_flat = backend.reshape(inputs, (backend.shape(inputs)[0], -1))
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kernel = kernel_mask * kernel
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kernel = make_2d(kernel, split_dim=backend.ndim(kernel) // 2)
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output_flat = tf.matmul(inputs_flat, kernel, b_is_sparse=True)
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output = backend.reshape(
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output_flat,
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[
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backend.shape(output_flat)[0],
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]
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+ output_shape.as_list()[1:],
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)
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return output
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def local_conv_sparse_matmul(
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inputs, kernel, kernel_idxs, kernel_shape, output_shape
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):
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"""Apply N-D convolution with unshared weights using a single sparse matmul.
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This method outputs `inputs . tf.sparse.SparseTensor(indices=kernel_idxs,
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values=kernel, dense_shape=kernel_shape)`, with `.` standing for
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matrix-multiply. It also reshapes `inputs` to 2-D and `output` to (N+2)-D.
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Args:
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inputs: (N+2)-D tensor with shape `(batch_size, channels_in, d_in1, ...,
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d_inN)` or `(batch_size, d_in1, ..., d_inN, channels_in)`.
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kernel: a 1-D tensor with shape `(len(kernel_idxs),)` containing all the
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weights of the layer.
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kernel_idxs: a list of integer tuples representing indices in a sparse
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matrix performing the un-shared convolution as a matrix-multiply.
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kernel_shape: a tuple `(input_size, output_size)`, where `input_size =
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channels_in * d_in1 * ... * d_inN` and `output_size = channels_out *
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d_out1 * ... * d_outN`.
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output_shape: a tuple of (N+2) elements representing the output shape:
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`(batch_size, channels_out, d_out1, ..., d_outN)` or `(batch_size,
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d_out1, ..., d_outN, channels_out)`, with the ordering of channels and
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spatial dimensions matching that of the input.
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Returns:
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Output (N+2)-D dense tensor with shape `output_shape`.
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"""
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inputs_flat = backend.reshape(inputs, (backend.shape(inputs)[0], -1))
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output_flat = tf.sparse.sparse_dense_matmul(
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sp_a=tf.SparseTensor(kernel_idxs, kernel, kernel_shape),
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b=inputs_flat,
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adjoint_b=True,
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)
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output_flat_transpose = backend.transpose(output_flat)
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output_reshaped = backend.reshape(
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output_flat_transpose,
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[
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backend.shape(output_flat_transpose)[0],
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]
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+ output_shape.as_list()[1:],
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)
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return output_reshaped
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def make_2d(tensor, split_dim):
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"""Reshapes an N-dimensional tensor into a 2D tensor.
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Dimensions before (excluding) and after (including) `split_dim` are grouped
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together.
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Args:
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tensor: a tensor of shape `(d0, ..., d(N-1))`.
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split_dim: an integer from 1 to N-1, index of the dimension to group
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dimensions before (excluding) and after (including).
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Returns:
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Tensor of shape
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`(d0 * ... * d(split_dim-1), d(split_dim) * ... * d(N-1))`.
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"""
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shape = tf.shape(tensor)
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in_dims = shape[:split_dim]
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out_dims = shape[split_dim:]
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in_size = tf.reduce_prod(in_dims)
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out_size = tf.reduce_prod(out_dims)
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return tf.reshape(tensor, (in_size, out_size))
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