BUG: ShortTimeFFT fails with complex input #20009
Description
Describe your issue.
ShortTimeFFT fails with complex input. The following reproduction uses a lightly modified version of the code from the example found in the documentation. The documentation states that the signal input x can be complex:
x
The input signal as real or complex valued array.
Thanks for all the team's efforts on this great project!
Reproducing Code Example
import numpy as np
import math # REZ10101 added
import matplotlib.pyplot as plt
from scipy.signal import ShortTimeFFT
from scipy.signal.windows import gaussian
T_x, N = 1 / 20, 1000 # 20 Hz sampling rate for 50 s signal
t_x = np.arange(N) * T_x # time indexes for signal
f_i = 1 * np.arctan((t_x - t_x[N // 2]) / 2) + 5
sig = 2*np.pi*np.cumsum(f_i)*T_x # REZ10101 split out
x = math.e ** (np.sin(sig) + 1j * np.cos(sig)) # REZ10101 made complex
g_std = 8 # standard deviation for Gaussian window in samples
w = gaussian(50, std=g_std, sym=True) # symmetric Gaussian window
SFT = ShortTimeFFT(w, hop=10, fs=1/T_x, mfft=200, scale_to='magnitude')
Sx = SFT.stft(x) # perform the STFT
fig1, ax1 = plt.subplots(figsize=(6., 4.)) # enlarge plot a bit
t_lo, t_hi = SFT.extent(N)[:2] # time range of plot
ax1.set_title(
rf"STFT ({SFT.m_num*SFT.T:g}$\,s$ Gaussian window, " +
rf"$\sigma_t={g_std*SFT.T}\,$s)"
)
ax1.set(
xlabel=(
f"Time $t$ in seconds ({SFT.p_num(N)} slices, " +
rf"$\Delta t = {SFT.delta_t:g}\,$s)"
),
ylabel=(
f"Freq. $f$ in Hz ({SFT.f_pts} bins, " +
rf"$\Delta f = {SFT.delta_f:g}\,$Hz)"
),
xlim=(t_lo, t_hi)
)
im1 = ax1.imshow(
abs(Sx),
origin='lower',
aspect='auto',
extent=SFT.extent(N),
cmap='viridis'
)
ax1.plot(t_x, f_i, 'r--', alpha=.5, label='$f_i(t)$')
fig1.colorbar(im1, label="Magnitude $|S_x(t, f)|$")
# Shade areas where window slices stick out to the side:
for t0_, t1_ in [(t_lo, SFT.lower_border_end[0] * SFT.T),
(SFT.upper_border_begin(N)[0] * SFT.T, t_hi)]:
ax1.axvspan(t0_, t1_, color='w', linewidth=0, alpha=.2)
for t_ in [0, N * SFT.T]: # mark signal borders with vertical line:
ax1.axvline(t_, color='y', linestyle='--', alpha=0.5)
ax1.legend()
fig1.tight_layout()
plt.show()Error message
Traceback (most recent call last):
File "/home/zuber/git/test/test_shortTimeFFT.py", line 24, in <module>
Sx = SFT.stft(x) # perform the STFT
^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/signal/_short_time_fft.py", line 795, in stft
return self.stft_detrend(x, None, p0, p1, k_offset=k_offset,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/signal/_short_time_fft.py", line 844, in stft_detrend
S[..., :, p_] = self._fft_func(x_ * self.win.conj())
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/signal/_short_time_fft.py", line 1583, in _fft_func
return fft_lib.rfft(x, n=self.mfft, axis=-1)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/fft/_backend.py", line 28, in __ua_function__
return fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/fft/_basic_backend.py", line 72, in rfft
return _execute_1D('rfft', _pocketfft.rfft, x, n=n, axis=axis, norm=norm,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/fft/_basic_backend.py", line 28, in _execute_1D
return pocketfft_func(x, n=n, axis=axis, norm=norm,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/zuber/git/venv/lib/python3.12/site-packages/scipy/fft/_pocketfft/basic.py", line 53, in r2c
raise TypeError("x must be a real sequence")
TypeError: x must be a real sequenceSciPy/NumPy/Python version and system information
Python 3.12.1 (main, Dec 10 2023, 15:16:41) [GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys, scipy, numpy; print(scipy.__version__, numpy.__version__, sys.version_info); scipy.show_config()
1.12.0 1.26.3 sys.version_info(major=3, minor=12, micro=1, releaselevel='final', serial=0)
/home/zuber/git/venv/lib/python3.12/site-packages/scipy/__config__.py:154: UserWarning: Install `pyyaml` for better output
warnings.warn("Install `pyyaml` for better output", stacklevel=1)
{
"Compilers": {
"c": {
"name": "gcc",
"linker": "ld.bfd",
"version": "10.2.1",
"commands": "cc"
},
"cython": {
"name": "cython",
"linker": "cython",
"version": "3.0.8",
"commands": "cython"
},
"c++": {
"name": "gcc",
"linker": "ld.bfd",
"version": "10.2.1",
"commands": "c++"
},
"fortran": {
"name": "gcc",
"linker": "ld.bfd",
"version": "10.2.1",
"commands": "gfortran"
},
"pythran": {
"version": "0.15.0",
"include directory": "../../tmp/pip-build-env-tfqmvy7q/overlay/lib/python3.12/site-packages/pythran"
}
},
"Machine Information": {
"host": {
"cpu": "x86_64",
"family": "x86_64",
"endian": "little",
"system": "linux"
},
"build": {
"cpu": "x86_64",
"family": "x86_64",
"endian": "little",
"system": "linux"
},
"cross-compiled": false
},
"Build Dependencies": {
"blas": {
"name": "openblas",
"found": true,
"version": "0.3.21.dev",
"detection method": "pkgconfig",
"include directory": "/usr/local/include",
"lib directory": "/usr/local/lib",
"openblas configuration": "USE_64BITINT= DYNAMIC_ARCH=1 DYNAMIC_OLDER= NO_CBLAS= NO_LAPACK= NO_LAPACKE= NO_AFFINITY=1 USE_OPENMP= HASWELL MAX_THREADS=2",
"pc file directory": "/usr/local/lib/pkgconfig"
},
"lapack": {
"name": "openblas",
"found": true,
"version": "0.3.21.dev",
"detection method": "pkgconfig",
"include directory": "/usr/local/include",
"lib directory": "/usr/local/lib",
"openblas configuration": "USE_64BITINT= DYNAMIC_ARCH=1 DYNAMIC_OLDER= NO_CBLAS= NO_LAPACK= NO_LAPACKE= NO_AFFINITY=1 USE_OPENMP= HASWELL MAX_THREADS=2",
"pc file directory": "/usr/local/lib/pkgconfig"
},
"pybind11": {
"name": "pybind11",
"version": "2.11.1",
"detection method": "config-tool",
"include directory": "unknown"
}
},
"Python Information": {
"path": "/opt/python/cp312-cp312/bin/python",
"version": "3.12"
}
}