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@ -1,5 +1,4 @@
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import numpy as np
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# from scipy.fftpack import _fftpack
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from scipy.fftpack import dct as _dct
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from scipy.fftpack import idct as _idct
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import os
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@ -8,17 +7,6 @@ path = os.path.dirname(os.path.realpath(__file__))
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__all__ = ['dct', 'idct', 'dctn', 'idctn']
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def _truncate_or_zero_pad(x, n, axis):
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nt = n - np.shape(x)[axis]
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if nt < 0:
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x = np.take(x, np.r_[0:n], axis=axis)
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elif 0 < nt:
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pads = [(0, 0)] * np.ndim(x)
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pads[axis] = 0, nt
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x = np.pad(x, pads, 'constant')
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return x
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def dct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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'''
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Return the Discrete Cosine Transform of arbitrary type sequence x.
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@ -71,7 +59,6 @@ def dct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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There are several definitions of the DCT-II; we use the following
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(for ``norm=None``)::
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N-1
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y[k] = 2* sum x[n]*cos(pi*k*(2n+1)/(2*N)), 0 <= k < N.
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n=0
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@ -115,7 +102,6 @@ def dct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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References
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----------
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http://en.wikipedia.org/wiki/Discrete_cosine_transform
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http://users.ece.utexas.edu/~bevans/courses/ee381k/lectures/
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@ -123,35 +109,7 @@ def dct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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Transactions on acoustics, speech and signal processing` vol. 28(1),
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pp. 27-34, http://dx.doi.org/10.1109/TASSP.1980.1163351 (1980).
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'''
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if n is not None:
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# Hack until scipy.fftpack.dct implement this functionality
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x = _truncate_or_zero_pad(x, n, axis)
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n = None
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# return _dct(x, type, n, axis, norm)
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dtype = np.result_type(np.float32, np.asarray(x))
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x0 = np.asarray(x, dtype=dtype)
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if dtype == complex:
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return (_dct(x0.real, type, n, axis, norm) + 1j *
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_dct(x0.imag, type, n, axis, norm))
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else:
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return _dct(x0, type, n, axis, norm)
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# def test(type=2, dtype=None, normalize='ortho'): # @ReservedAssignment
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# dtype = np.result_type(np.float64)
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# try:
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# nm = {None: 0, 'ortho': 1}[normalize]
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# except KeyError:
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# raise ValueError("Unknown normalize mode %s" % normalize)
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# try:
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# name = {'float64': 'ddct%d', 'float32': 'dct%d'}[dtype.name]
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# except KeyError:
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# raise ValueError("dtype %s not supported" % dtype)
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# try:
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# f = getattr(_fftpack, name % type)
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# except AttributeError as e:
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# raise ValueError(str(e) + ". Type %d not understood" % type)
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# return f, nm
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return _dct(x, type, n, axis, norm)
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def idct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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@ -191,17 +149,7 @@ def idct(x, type=2, n=None, axis=-1, norm='ortho'): # @ReservedAssignment
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and IDCT of type 3 is the DCT of type 2. For the definition of these types,
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see `dct`.
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'''
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farr = np.asarray
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if n is not None:
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# Hack until scipy.fftpack.idct implement this functionality
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x = _truncate_or_zero_pad(x, n, axis)
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n = None
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if np.iscomplex(x).any():
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x0 = farr(x, dtype=complex)
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return (_idct(x0.real, type, n, axis, norm) + 1j *
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_idct(x0.imag, type, n, axis, norm))
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else:
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return _idct(farr(x, dtype=float), type, n, axis, norm)
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return _idct(x, type, n, axis, norm)
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def _get_shape(y, shape, axes):
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@ -488,9 +436,9 @@ def test_commands():
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if __name__ == '__main__':
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print(test_commands())
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# print(test_commands())
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# test_dct2()
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# test_docstrings()
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test_docstrings()
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# test_dctn()
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# test_shiftdim()
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# test_dct3()
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