def bilinear_pool(x1, x2, x3, output_size):
""" Computes approximation of bilinear pooling with respect to x1, x2.
For detailed explaination, see the paper (https://arxiv.org/abs/1511.06062)
Args:
x1: A `Tensor` with shape (batch_size, x1_size).
x2: A `Tensor` with shape ((batch_size, x2_size).
output_size: Output projection size. (`int`)
Returns:
A Tensor with shape (batch_size, output_size).
"""
p1 = count_sketch(x1, output_size)
p2 = count_sketch(x2, output_size)
p3 = count_sketch(x3, output_size)
pc1 = tf.complex(p1, tf.zeros_like(p1))
pc2 = tf.complex(p2, tf.zeros_like(p2))
pc3 = tf.complex(p3, tf.zeros_like(p3))
conved = tf.ifft(tf.fft(pc1) * tf.fft(pc2) * tf.fft(pc3))
conved2 = tf.ifft(tf.fft(pc1) * tf.fft(pc2) * tf.fft(pc3) * 1)
return tf.real(conved), tf.real(conved2)
def deconv(comb_loss, loss_a, loss_b):
x = tf.cast(comb_loss[:, 0], dtype=tf.complex64)
y = tf.cast(comb_loss[:, 1], dtype=tf.complex64)
yfft = tf.fft(y)
ay = tf.cast(loss_a[:, 1], dtype=tf.complex64)
by = tf.cast(loss_b[:, 1], dtype=tf.complex64)
ayfft = tf.fft(ay)
byfft = tf.fft(by)
ayfftest = yfft / byfft
ayest = tf.abs(tf.ifft(ayfftest))
aest = tf.cast(tf.abs(tf.ifft(ayfft)), dtype=tf.float64)
best = tf.cast(tf.abs(tf.ifft(byfft)), dtype=tf.float64)
return best
def istft(spec, overlap=4):
assert (spec.shape[0] > 1)
S = placeholder(dtype=tf.complex64, shape=spec.shape)
X = tf.complex_abs(tf.concat(0, [tf.ifft(frame) \
for frame in tf.unstack(S)]))
sess = tf.Session()
return sess.run(X, feed_dict={S: spec})
def model(self, sinogram):
"""
main model for the FDK algorithm
Parameters
----------
sinogram : ndarray
The projection data used for reconstruction
Returns
-------
ndarray
the reconstructed CT data
"""
sinogram_cos = tf.multiply(sinogram, self.cosine_weight)
weighted_sino_fft = tf.fft(tf.cast(sinogram_cos, dtype=tf.complex64))
filtered_sinogram_fft = tf.multiply(
weighted_sino_fft, tf.cast(self.filter, dtype=tf.complex64))
filtered_sinogram = tf.real(tf.ifft(filtered_sinogram_fft))
reconstruction = cone_backprojection3d(filtered_sinogram,
self.geometry,
hardware_interp=True)
return reconstruction
def _get_w(self, last_w, raw_output, memory):
with tf.variable_scope('get_w'):
k, beta, g, s, gamma = tf.split(
raw_output, [self.M, self.N, 1, self.N, self.N], axis=1)
# memory_row_norm = tf.reduce_sum(tf.abs(memory), axis=1)
memory = tf.nn.l2_normalize(memory, axis=1)
k = tf.nn.l2_normalize(k, axis=1)
product = tf.squeeze(tf.matmul(tf.expand_dims(k, 1), memory))
# omit division of `k` since it is canceled after softmax anyway
beta = tf.nn.softplus(beta, name='beta')
# w_c = tf.nn.softmax(beta * product / memory_row_norm, name='w_c')
w_c = tf.nn.softmax(beta * product, name='w_c')
g = tf.sigmoid(g, name='gate_parameter')
w_g = tf.add(g * w_c, (1 - g) * last_w, name='w_g')
w_g = tf.cast(w_g, tf.complex64)
# s = tf.cast(tf.nn.softmax(s), tf.complex64)
s = tf.cast(tf.tanh(s, name='shift'), tf.complex64)
w_tild = tf.real(tf.ifft(tf.fft(w_g) * tf.fft(s)), name='w_tild')
gamma = tf.add(tf.nn.softplus(gamma), 1, name='gamma')
# w = tf.pow(w_tild, gamma)
# w = w / tf.reduce_sum(w)
# FIXME: tf.log yields lots of NaN here!!
# w = tf.nn.softmax(gamma * tf.log(tf.nn.softmax(w_tild)))
w = tf.nn.softmax(gamma * tf.log(tf.nn.softplus(w_tild)),
name='new_weight')
# w = tf.nn.softmax(gamma * tf.log(tf.nn.sigmoid(w_tild)))
# w = tf.nn.softmax(gamma * w_tild)
return w
def bandPass(signal, low_cut, high_cut, sample_length, sample_rate):
'''
band pass filter
args:
signal = input signal
low_cut = filtering bandwidth Hz (lower bound)
high_cut = filtering bandwidth Hz (upper bound)
sample_length = total signal length (number of samples)
sample_rate = sampling rate of the input signal
return:
filtered.real = filtered signal
'''
ratio = int(sample_length / sample_rate)
with tf.Graph().as_default():
signal = tf.Variable(signal, dtype=tf.complex64)
fft = tf.fft(signal)
with tf.Session() as sess:
tf.variables_initializer([signal]).run()
result = sess.run(fft)
for i in range(high_cut * ratio,
len(result) - (high_cut * ratio) + 1):
result[i] = 0
for i in range(0, (low_cut * ratio) + 1):
result[i] = 0
for i in range(len(result) - (low_cut * ratio), len(result)):
result[i] = 0
ifft = tf.ifft(result)
with tf.Session() as sess:
filtered = sess.run(ifft)
return filtered.real
def lowPass(signal, cut, sample_length, sample_rate):
'''
low pass filter
args:
signal = input signal
cut = filtering bandwidth Hz
sample_length = total signal length (number of samples)
sample_rate = sampling rate of the input signal
return:
filtered.real = filtered signal
'''
ratio = int(sample_length / sample_rate)
with tf.Graph().as_default():
signal = tf.Variable(signal, dtype=tf.complex64)
fft = tf.fft(signal)
with tf.Session() as sess:
tf.variables_initializer([signal]).run()
result = sess.run(fft)
for i in range(cut * ratio,
len(result) - (cut * ratio) +
1): #what is the intuition behind this??
result[i] = 0
ifft = tf.ifft(result)
with tf.Session() as sess:
filtered = sess.run(ifft)
return filtered.real
def istft(inp, n_overlap):
inp_sz = inp.get_shape().as_list()
if len(inp_sz) > 3:
inp = tf.reshape(inp, (np.prod(inp_sz[:-2]), inp_sz[-2], inp_sz[-1]))
batch_size, n_frames, n_freqs = inp.get_shape().as_list()
n_frames = int(int(float(n_frames) / n_overlap) * n_overlap)
inp = inp[:, :n_frames, :]
batch_size, n_frames, n_freqs = inp.get_shape().as_list()
x = tf.real(tf.ifft(inp))
x = tf.reshape(x, (batch_size, -1, n_overlap, n_freqs))
x = tf.transpose(x, (0, 2, 1, 3))
x = tf.reshape(x, (batch_size, n_overlap, -1))
x_list = tf.unstack(x, axis=1)
skip = n_freqs / n_overlap
for i in range(n_overlap):
# x_sep[i] = tf.manip.roll(x_sep[i], i*wind_size/4, 2)
if i == 0:
x_list[i] = x_list[i][:, (n_overlap - i - 1) * skip:]
else:
x_list[i] = x_list[i][:, (n_overlap - i - 1) * skip:-i * skip]
x = tf.add_n(x_list) / float(n_overlap)
if len(inp_sz) > 3:
x_sz = x.get_shape().as_list()
x = tf.reshape(x, inp_sz[:-2] + x_sz[-1:])
return x
def forward_proj_domain(self, sinogram):
"""
the projection domain of the model for processing sinograms
Parameters
----------
sinogram : ndarray
The projection data used for processing and reconstruction
Returns
-------
ndarray
the sinograms after processing
"""
# U-Net added in the projection domain
####################################################################
sinogram = tf.expand_dims(sinogram, 3)
sinogram = self.unet_model(sinogram)
sinogram = tf.squeeze(sinogram, axis=3)
####################################################################
self.sinogram_cosine = tf.multiply(sinogram, self.cosine_weight)
self.weighted_sinogram_fft = tf.fft(
tf.cast(self.sinogram_cosine, dtype=tf.complex64))
self.filtered_sinogram_fft = tf.multiply(
self.weighted_sinogram_fft,
tf.cast(self.recon_filter, dtype=tf.complex64))
self.filtered_sinogram = tf.real(tf.ifft(self.filtered_sinogram_fft))
return self.filtered_sinogram
def tensor_product(self, P, ch1, Q, ch2):
P_hat = tf.fft(tf.complex(P, tf.zeros(tf.shape(P), dtype=tf.float32)))
Q_hat = tf.fft(tf.complex(Q, tf.zeros(tf.shape(Q), dtype=tf.float32)))
p_hat_list = [tf.squeeze(p) for p in tf.split(P_hat, self.k, axis=-1)]
q_hat_list = [tf.squeeze(q) for q in tf.split(Q_hat, self.k, axis=-1)]
if ch1 == 't' and ch2 == 't':
S_hat = tf.concat([
tf.expand_dims(tf.matmul(tf.transpose(p_hat),
tf.transpose(q_hat)),
axis=-1)
for (p_hat, q_hat) in zip(p_hat_list, q_hat_list)
],
axis=-1)
elif ch1 == 't':
S_hat = tf.concat([
tf.expand_dims(tf.matmul(tf.transpose(p_hat), q_hat), axis=-1)
for (p_hat, q_hat) in zip(p_hat_list, q_hat_list)
],
axis=-1)
elif ch2 == 't':
S_hat = tf.concat([
tf.expand_dims(tf.matmul(p_hat, tf.transpose(q_hat)), axis=-1)
for (p_hat, q_hat) in zip(p_hat_list, q_hat_list)
],
axis=-1)
else:
S_hat = tf.concat([
tf.expand_dims(tf.matmul(p_hat, q_hat), axis=-1)
for (p_hat, q_hat) in zip(p_hat_list, q_hat_list)
],
axis=-1)
return tf.real(tf.ifft(S_hat))
def est_kernel(blurs, deblurs, nstd=2, ksz=27):
assert ksz % 2 == 1
hksz = (ksz - 1) // 2
if nstd == 0:
nstd = 1e-6
blurs = tf.cast(tf.transpose(blurs, [0, 3, 1, 2]), tf.complex64)
deblurs = tf.cast(tf.transpose(deblurs, [0, 3, 1, 2]), tf.complex64)
fft_blurs = tf.fft2d(blurs)
fft_deblurs = tf.fft2d(deblurs)
numerator = fft_deblurs * tf.conj(fft_blurs)
denominator = tf.abs(fft_blurs)**2 + (nstd / 255.)**2.
out = tf.real(tf.ifft(numerator / denominator))
out = tf.transpose(out, [0, 2, 3, 1])
out1 = tf.concat([out[:, -hksz:, -hksz:], out[:, :hksz + 1, -hksz:]],
axis=1)
out2 = tf.concat([out[:, -hksz:, :hksz + 1], out[:, :hksz + 1, :hksz + 1]],
axis=1)
kernels = tf.concat([out1, out2], axis=2)
kernels = kernels / tf.reduce_mean(kernels, axis=[1, 2])
return kernels
def fft_to_audio(fft):
return_values = []
with tf.variable_scope("fft_to_audio", reuse=fft_to_audio_init):
input = tf.placeholder(tf.complex64, [fft.shape[1]])
zeroes = tf.fill([int(fft_size / 2) - int(input.shape[0])],
input[-1] * 0)
fill = tf.concat([input, zeroes], axis=0)
inverse = tf.reverse(tf.conj(fill), [0])
full = tf.concat([fill, inverse[-2:-1], inverse[:-1]], axis=-1)
output = tf.cast(tf.ifft(full), tf.float32)
sess = tf.get_default_session()
steps = fft.shape[0]
for i in range(steps):
feed_audio = fft[i, :]
values = sess.run({"output": output},
feed_dict={input: feed_audio})
output_values = values["output"]
return_values.append(output_values)
global fft_to_audio_init
fft_to_audio_init = True
return np.concatenate(return_values, axis=0)
def call(self, x):
p1 = self.count_sketch(x[:, :img_dim], self.output_dim, self.h1, self.s1)
p2 = self.count_sketch(x[:, img_dim:], self.output_dim, self.h2, self.s2)
pc1 = tf.complex(p1, tf.zeros_like(p1))
pc2 = tf.complex(p2, tf.zeros_like(p2))
conved = tf.ifft(tf.fft(pc1) * tf.fft(pc2))
return tf.real(conved)
def ifftc(im, name="ifftc", do_orthonorm=True):
"""Centered iFFT on second to last dimension."""
with tf.name_scope(name):
im_out = im
if do_orthonorm:
fftscale = tf.sqrt(1.0 * im_out.get_shape().as_list()[-2])
else:
fftscale = 1.0
fftscale = tf.cast(fftscale, dtype=tf.complex64)
if len(im.get_shape()) == 4:
im_out = tf.transpose(im_out, [0, 3, 1, 2])
im_out = fftshift(im_out, axis=3)
else:
im_out = tf.transpose(im_out, [2, 0, 1])
im_out = fftshift(im_out, axis=2)
with tf.device('/gpu:0'):
# FFT is only supported on the GPU
im_out = tf.ifft(im_out) * fftscale
if len(im.get_shape()) == 4:
im_out = fftshift(im_out, axis=3)
im_out = tf.transpose(im_out, [0, 2, 3, 1])
else:
im_out = fftshift(im_out, axis=2)
im_out = tf.transpose(im_out, [1, 2, 0])
return im_out
def hilbert(xr):
'''
Implements the hilbert transform, a mapping from C to R.
Args:
xr: The input sequence.
Returns:
xc: A complex sequence of the same length.
'''
with tf.variable_scope('hilbert_transform'):
n = tf.Tensor.get_shape(xr).as_list()[0]
# Run the fft on the columns no the rows.
x = tf.transpose(tf.fft(tf.transpose(xr)))
h = np.zeros([n])
if n > 0 and 2*np.fix(n/2) == n:
# even and nonempty
h[0:int(n/2+1)] = 1
h[1:int(n/2)] = 2
elif n > 0:
# odd and nonempty
h[0] = 1
h[1:int((n+1)/2)] = 2
tf_h = tf.constant(h, name='h', dtype=tf.float32)
if len(x.shape) == 2:
hs = np.stack([h]*x.shape[-1], -1)
reps = tf.Tensor.get_shape(x).as_list()[-1]
hs = tf.stack([tf_h]*reps, -1)
elif len(x.shape) == 1:
hs = tf_h
else:
raise NotImplementedError
tf_hc = tf.complex(hs, tf.zeros_like(hs))
xc = x*tf_hc
return tf.transpose(tf.ifft(tf.transpose(xc)))
def fftc(im,
data_format='channels_last',
orthonorm=True,
transpose=False,
name='fftc'):
"""Centered FFT on last non-channel dimension."""
with tf.name_scope(name):
im_out = im
if data_format == 'channels_last':
permute_orig = np.arange(len(im.shape))
permute = permute_orig.copy()
permute[-2] = permute_orig[-1]
permute[-1] = permute_orig[-2]
im_out = tf.transpose(im_out, permute)
if orthonorm:
fftscale = tf.sqrt(tf.cast(im_out.shape[-1], tf.float32))
else:
fftscale = 1.0
fftscale = tf.cast(fftscale, dtype=tf.complex64)
im_out = fftshift(im_out, axis=-1)
if transpose:
im_out = tf.ifft(im_out) * fftscale
else:
im_out = tf.fft(im_out) / fftscale
im_out = fftshift(im_out, axis=-1)
if data_format == 'channels_last':
im_out = tf.transpose(im_out, permute)
return im_out
def forward_proj_domain(self, sinogram):
"""
the projection domain of the model for processing sinograms
Parameters
----------
sinogram : ndarray
The projection data used for processing and reconstruction
Returns
-------
ndarray
the sinograms after processing
"""
self.sinogram_cosine = tf.multiply(sinogram, self.cosine_weight)
self.weighted_sinogram_fft = tf.fft(
tf.cast(self.sinogram_cosine, dtype=tf.complex64))
self.filtered_sinogram_fft = tf.multiply(
self.weighted_sinogram_fft,
tf.cast(self.recon_filter, dtype=tf.complex64))
self.filtered_sinogram = tf.real(tf.ifft(self.filtered_sinogram_fft))
return self.filtered_sinogram
def _matmul(self, X_fft, w):
w = tf.cast(w, tf.complex64)
fft_w = tf.fft(w[..., ::-1])
fft_mul = tf.multiply(X_fft, fft_w)
ifft_val = tf.ifft(fft_mul)
mat = tf.cast(tf.real(ifft_val), tf.float32)
mat = tf.manip.roll(mat, shift=1, axis=1)
return mat
def circular_cross_correlation(x, y):
"""Periodic correlation, implemented using the FFT.
x and y must be of the same length.
"""
return tf.real(
tf.ifft(
tf.multiply(tf.conj(tf.fft(tf.cast(x, tf.complex64))),
tf.fft(tf.cast(y, tf.complex64)))))
def one_layer(X_real, X_image, W1_real, W1_image, W2_real, W2_image, alph, ii):
## High memory consuming
all_zeros = tf.zeros([k + 1], tf.float32)
ones = tf.ones([k + 1], tf.bool)
zeros = tf.zeros([k + 1], tf.bool)
sliced_zeros = tf.slice(zeros, [ii], [k + 1 - ii])
sliced_ones = tf.slice(ones, [0], [ii])
mask = tf.concat((sliced_ones, sliced_zeros), axis=0)
W1_real = tf.where(mask, all_zeros, W1_real)
W1_image = tf.where(mask, all_zeros, W1_image)
W1_real = Weight_Transform(W1_real, k=k, n=N)
W1_image = Weight_Transform(W1_image, k=k, n=N)
W2_real = tf.where(mask, all_zeros, W2_real)
W2_image = tf.where(mask, all_zeros, W2_image)
W2_real = Weight_Transform(W2_real, k=k, n=N)
W2_image = Weight_Transform(W2_image, k=k, n=N)
X_complex_fft = tf.fft(tf.complex(X_real, X_image))
W1_complex_fft = tf.fft(tf.complex(W1_real, W1_image))
X_complex = tf.ifft(X_complex_fft * W1_complex_fft)
X_real = tf.math.real(X_complex)
X_image = tf.math.imag(X_complex)
# None-linear
S_power = tf.math.add(tf.math.square(X_real), tf.math.square(X_image))
S_power = tf.math.scalar_mul(alph, S_power)
sin = tf.math.sin(S_power)
cos = tf.math.cos(S_power)
X_real = tf.math.subtract(tf.math.multiply(X_real, cos),
tf.math.multiply(X_image, sin))
X_image = tf.math.add(tf.math.multiply(X_image, cos),
tf.math.multiply(X_real, sin))
# W2
X_complex_fft = tf.fft(tf.complex(X_real, X_image))
W2_complex_fft = tf.fft(tf.complex(W2_real, W2_image))
X_complex = tf.ifft(X_complex_fft * W2_complex_fft)
out_real = tf.math.real(X_complex)
out_image = tf.math.imag(X_complex)
return out_real, out_image
def cconv(x, y):
x_fft_ = tf.fft(tf.complex(x,0.0))
#e2_fft_ = tf.fft(tf.complex(tf.nn.l2_normalize(self.e2, axis=2),0.0))
y_fft_ = tf.fft(tf.complex(y,0.0))
x_fft = x_fft_ #+ tf.complex(tf.to_float(tf.equal(x_fft_, 0.)),0.)*no_zeros
y_fft = y_fft_ #+ tf.complex(tf.to_float(tf.equal(y_fft_, 0.)),0.)*no_zeros
return tf.cast(tf.real(tf.ifft(tf.multiply(tf.conj(x_fft),\
y_fft))),dtype=tf.float32)
def circular_corr(a, b, name=''):
name = get_name(name, 'circular_corr')
with tf.name_scope(name):
a_fft = tf.conj(tf.fft(tf.complex(a, 0.0)))
b_fft = tf.fft(tf.complex(b, 0.0))
ifft = tf.ifft(a_fft * b_fft)
res = tf.cast(tf.real(ifft), 'float32')
return res
def triple_linear_pool(x1, x2, x3, output_size):
p1 = count_sketch(x1, output_size)
p2 = count_sketch(x2, output_size)
p3 = count_sketch(x3, output_size)
pc1 = tf.complex(p1, tf.zeros_like(p1))
pc2 = tf.complex(p2, tf.zeros_like(p2))
pc3 = tf.complex(p3, tf.zeros_like(p3))
conved = tf.ifft(tf.fft(pc1) * tf.fft(pc2) * tf.fft(pc3))
return tf.real(conved)
def extract_cochlear_subbands(nets, SIGNAL_SIZE, SR, LOW_LIM, HIGH_LIM, N, SAMPLE_FACTOR, pad_factor, rFFT, custom_filts, erb_filter_kwargs, include_all_keys, compression_function):
"""
Computes the cochlear subbands from the fft of the input signal
Parameters
----------
nets : dictionary
dictionary containing parts of the cochleagram graph. 'fft_input' is multiplied by the cochlear filters
SIGNAL_SIZE : int
the length of the audio signal used for the cochleagram graph
SR : int
raw sampling rate in Hz for the audio.
LOW_LIM : int
Lower frequency limits for the filters.
HIGH_LIM : int
Higher frequency limits for the filters.
N : int
Number of filters to uniquely span the frequency space
SAMPLE_FACTOR : int
number of times to overcomplete the filters.
N : int
Number of filters to uniquely span the frequency space
SAMPLE_FACTOR : int
number of times to overcomplete the filters.
pad_factor : int
how much padding to add to the signal. Follows conventions of pycochleagram (ie pad of 2 doubles the signal length)
rFFT : Boolean
If true, cochleagram graph is constructed using rFFT wherever possible
custom_filts : None, or numpy array
if not None, a numpy array containing the filters to use for the cochleagram generation. If none, uses erb.make_erb_cos_filters from pycochleagram to construct the filterbank. If using rFFT, should contain th full filters, shape [SIGNAL_SIZE, NUMBER_OF_FILTERS]
erb_filter_kwargs : dictionary
contains additional arguments with filter parameters to use with erb.make_erb_cos_filters
include_all_keys : Boolean
If True, includes the time subbands and the cochleagram in the dictionary keys
compression_function : function
A partial function that takes in nets and the input and output names to apply compression
Returns
-------
nets : dictionary
updated dictionary containing parts of the cochleagram graph.
"""
# make the erb filters tensor
nets['filts_tensor'] = make_filts_tensor(SIGNAL_SIZE, SR, LOW_LIM, HIGH_LIM, N, SAMPLE_FACTOR, use_rFFT=rFFT, pad_factor=pad_factor, custom_filts=custom_filts, erb_filter_kwargs=erb_filter_kwargs)
# make subbands by multiplying filts with fft of input
nets['subbands'] = tf.multiply(nets['filts_tensor'],nets['fft_input'],name='mul_subbands')
# make the time the keys in the graph if we are returning all keys (otherwise, only return the subbands in fourier domain)
if include_all_keys:
if not rFFT:
nets['subbands_ifft'] = tf.real(tf.ifft(nets['subbands'],name='ifft_subbands'),name='ifft_subbands_r')
else:
nets['subbands_ifft'] = tf.spectral.irfft(nets['subbands'],name='ifft_subbands')
nets['subbands_time'] = nets['subbands_ifft']
return nets
def _fft_solver(self, grad, varname):
grad_shape = grad.shape.as_list()
N, coef = self._var_info_dict[varname]
grad = tf.reshape(grad, shape=[N])
grad = tf.cast(grad, tf.complex64)
# import ipdb; ipdb.set_trace()
grad = tf.real(ifft(fft(grad) * coef))
grad = tf.reshape(grad, shape=grad_shape)
return grad
def update_x_step(z):
result_x_step = kt_y * u + z
result_x_step = tf.cast(result_x_step, tf.complex128)
result_x_step = tf.fft(result_x_step)
result_x_step = result_x_step / fre_k
result_x_step = tf.ifft(result_x_step)
result_x_step = tf.abs(result_x_step)
return result_x_step
def backward_fft(x):
print(x.shape)
real, imag = tf.split(x, num_or_size_splits=2, axis=1)
x_complex = tf.complex(real, imag)
x_complex = tf.ifft(x_complex)
x_real = tf.cast(tf.abs(x_complex), dtype=tf.float32)
return x_real
def combine_and_inverse_fft(args):
abs_branch, angle_branch = args
real = abs_branch * tf.cos(angle_branch)
imag = abs_branch * tf.sin(angle_branch)
x_complex = tf.complex(real, imag)
x_reverse = tf.real(tf.ifft(x_complex))
return x_reverse
def _ifft(bottom, sequential, compute_size):
'''
Return
------
iFFT(bottom), has the same shape of bottom
'''
if sequential:
return sequential_batch_ifft(bottom, compute_size)
else:
return tf.ifft(bottom)
def tf_ifft(tensor, shift, axis=0):
shifted = tf.manip.roll(tensor, shift=shift, axis=axis)
# fft
time_domain_not_shifted = tf.ifft(shifted)
# shift again
time_domain = tf.manip.roll(time_domain_not_shifted,
shift=shift,
axis=axis)
return time_domain
def op(self):
xf = tensorflow.fft(self.x)
x2 = xf * tensorflow.conj(xf)
xt = tensorflow.ifft(x2)
xr = 10*tensorflow.log( tensorflow.abs( xt[:,0:self.aclen] ) )
if self.avg:
N = tensorflow.shape(xr)[0]
idx = tensorflow.cast(tensorflow.range(0,N), tensorflow.float32)
s = tensorflow.reshape( self.alpha * tensorflow.pow( (1-self.alpha), idx ), [N,1] )
self.u = tensorflow.pow( (1-self.alpha), tensorflow.cast(N,tensorflow.float32) )*self.u + tensorflow.reduce_sum(s*xr, 0)
return self.u
else:
return xr
def auto_correlation(
x,
axis=-1,
max_lags=None,
center=True,
normalize=True,
name="auto_correlation"):
"""Auto correlation along one axis.
Given a `1-D` wide sense stationary (WSS) sequence `X`, the auto correlation
`RXX` may be defined as (with `E` expectation and `Conj` complex conjugate)
```
RXX[m] := E{ W[m] Conj(W[0]) } = E{ W[0] Conj(W[-m]) },
W[n] := (X[n] - MU) / S,
MU := E{ X[0] },
S**2 := E{ (X[0] - MU) Conj(X[0] - MU) }.
```
This function takes the viewpoint that `x` is (along one axis) a finite
sub-sequence of a realization of (WSS) `X`, and then uses `x` to produce an
estimate of `RXX[m]` as follows:
After extending `x` from length `L` to `inf` by zero padding, the auto
correlation estimate `rxx[m]` is computed for `m = 0, 1, ..., max_lags` as
```
rxx[m] := (L - m)**-1 sum_n w[n + m] Conj(w[n]),
w[n] := (x[n] - mu) / s,
mu := L**-1 sum_n x[n],
s**2 := L**-1 sum_n (x[n] - mu) Conj(x[n] - mu)
```
The error in this estimate is proportional to `1 / sqrt(len(x) - m)`, so users
often set `max_lags` small enough so that the entire output is meaningful.
Note that since `mu` is an imperfect estimate of `E{ X[0] }`, and we divide by
`len(x) - m` rather than `len(x) - m - 1`, our estimate of auto correlation
contains a slight bias, which goes to zero as `len(x) - m --> infinity`.
Args:
x: `float32` or `complex64` `Tensor`.
axis: Python `int`. The axis number along which to compute correlation.
Other dimensions index different batch members.
max_lags: Positive `int` tensor. The maximum value of `m` to consider
(in equation above). If `max_lags >= x.shape[axis]`, we effectively
re-set `max_lags` to `x.shape[axis] - 1`.
center: Python `bool`. If `False`, do not subtract the mean estimate `mu`
from `x[n]` when forming `w[n]`.
normalize: Python `bool`. If `False`, do not divide by the variance
estimate `s**2` when forming `w[n]`.
name: `String` name to prepend to created ops.
Returns:
`rxx`: `Tensor` of same `dtype` as `x`. `rxx.shape[i] = x.shape[i]` for
`i != axis`, and `rxx.shape[axis] = max_lags + 1`.
Raises:
TypeError: If `x` is not a supported type.
"""
# Implementation details:
# Extend length N / 2 1-D array x to length N by zero padding onto the end.
# Then, set
# F[x]_k := sum_n x_n exp{-i 2 pi k n / N }.
# It is not hard to see that
# F[x]_k Conj(F[x]_k) = F[R]_k, where
# R_m := sum_n x_n Conj(x_{(n - m) mod N}).
# One can also check that R_m / (N / 2 - m) is an unbiased estimate of RXX[m].
# Since F[x] is the DFT of x, this leads us to a zero-padding and FFT/IFFT
# based version of estimating RXX.
# Note that this is a special case of the Wiener-Khinchin Theorem.
with tf.name_scope(name, values=[x]):
x = tf.convert_to_tensor(x, name="x")
# Rotate dimensions of x in order to put axis at the rightmost dim.
# FFT op requires this.
rank = util.prefer_static_rank(x)
if axis < 0:
axis = rank + axis
shift = rank - 1 - axis
# Suppose x.shape[axis] = T, so there are T "time" steps.
# ==> x_rotated.shape = B + [T],
# where B is x_rotated's batch shape.
x_rotated = util.rotate_transpose(x, shift)
if center:
x_rotated -= tf.reduce_mean(x_rotated, axis=-1, keepdims=True)
# x_len = N / 2 from above explanation. The length of x along axis.
# Get a value for x_len that works in all cases.
x_len = util.prefer_static_shape(x_rotated)[-1]
# TODO(langmore) Investigate whether this zero padding helps or hurts. At
# the moment is is necessary so that all FFT implementations work.
# Zero pad to the next power of 2 greater than 2 * x_len, which equals
# 2**(ceil(Log_2(2 * x_len))). Note: Log_2(X) = Log_e(X) / Log_e(2).
x_len_float64 = tf.cast(x_len, np.float64)
target_length = tf.pow(
np.float64(2.), tf.ceil(tf.log(x_len_float64 * 2) / np.log(2.)))
pad_length = tf.cast(target_length - x_len_float64, np.int32)
# We should have:
# x_rotated_pad.shape = x_rotated.shape[:-1] + [T + pad_length]
# = B + [T + pad_length]
x_rotated_pad = util.pad(x_rotated, axis=-1, back=True, count=pad_length)
dtype = x.dtype
if not dtype.is_complex:
if not dtype.is_floating:
raise TypeError("Argument x must have either float or complex dtype"
" found: {}".format(dtype))
x_rotated_pad = tf.complex(x_rotated_pad,
dtype.real_dtype.as_numpy_dtype(0.))
# Autocorrelation is IFFT of power-spectral density (up to some scaling).
fft_x_rotated_pad = tf.fft(x_rotated_pad)
spectral_density = fft_x_rotated_pad * tf.conj(fft_x_rotated_pad)
# shifted_product is R[m] from above detailed explanation.
# It is the inner product sum_n X[n] * Conj(X[n - m]).
shifted_product = tf.ifft(spectral_density)
# Cast back to real-valued if x was real to begin with.
shifted_product = tf.cast(shifted_product, dtype)
# Figure out if we can deduce the final static shape, and set max_lags.
# Use x_rotated as a reference, because it has the time dimension in the far
# right, and was created before we performed all sorts of crazy shape
# manipulations.
know_static_shape = True
if not x_rotated.shape.is_fully_defined():
know_static_shape = False
if max_lags is None:
max_lags = x_len - 1
else:
max_lags = tf.convert_to_tensor(max_lags, name="max_lags")
max_lags_ = tensor_util.constant_value(max_lags)
if max_lags_ is None or not know_static_shape:
know_static_shape = False
max_lags = tf.minimum(x_len - 1, max_lags)
else:
max_lags = min(x_len - 1, max_lags_)
# Chop off the padding.
# We allow users to provide a huge max_lags, but cut it off here.
# shifted_product_chopped.shape = x_rotated.shape[:-1] + [max_lags]
shifted_product_chopped = shifted_product[..., :max_lags + 1]
# If possible, set shape.
if know_static_shape:
chopped_shape = x_rotated.shape.as_list()
chopped_shape[-1] = min(x_len, max_lags + 1)
shifted_product_chopped.set_shape(chopped_shape)
# Recall R[m] is a sum of N / 2 - m nonzero terms x[n] Conj(x[n - m]). The
# other terms were zeros arising only due to zero padding.
# `denominator = (N / 2 - m)` (defined below) is the proper term to
# divide by by to make this an unbiased estimate of the expectation
# E[X[n] Conj(X[n - m])].
x_len = tf.cast(x_len, dtype.real_dtype)
max_lags = tf.cast(max_lags, dtype.real_dtype)
denominator = x_len - tf.range(0., max_lags + 1.)
denominator = tf.cast(denominator, dtype)
shifted_product_rotated = shifted_product_chopped / denominator
if normalize:
shifted_product_rotated /= shifted_product_rotated[..., :1]
# Transpose dimensions back to those of x.
return util.rotate_transpose(shifted_product_rotated, -shift)
def _cconv(self, a, b): return tf.ifft(tf.fft(a) * tf.fft(b)).real
def _ccorr(self, a, b): a = tf.cast(a, tf.complex64) b = tf.cast(b, tf.complex64) return tf.real(tf.ifft(tf.conj(tf.fft(a)) * tf.fft(b)))