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Classe « ShortTimeFFT »

Méthode scipy.signal.ShortTimeFFT.from_window

Signature de la méthode from_window

def from_window(win_param: str | tuple | float, fs: float, nperseg: int, noverlap: int, *, symmetric_win: bool = False, fft_mode: Literal['twosided', 'centered', 'onesided', 'onesided2X'] = 'onesided', mfft: int | None = None, scale_to: Optional[Literal['magnitude', 'psd']] = None, phase_shift: int | None = 0) 

Description

help(ShortTimeFFT.from_window)

Instantiate `ShortTimeFFT` by using `get_window`.

The method `get_window` is used to create a window of length
`nperseg`. The parameter names `noverlap`, and `nperseg` are used here,
since they more inline with other classical STFT libraries.

Parameters
----------
win_param: Union[str, tuple, float],
    Parameters passed to `get_window`. For windows with no parameters,
    it may be a string (e.g., ``'hann'``), for parametrized windows a
    tuple, (e.g., ``('gaussian', 2.)``) or a single float specifying
    the shape parameter of a kaiser window (i.e. ``4.``  and
    ``('kaiser', 4.)`` are equal. See `get_window` for more details.
fs : float
    Sampling frequency of input signal. Its relation to the
    sampling interval `T` is ``T = 1 / fs``.
nperseg: int
    Window length in samples, which corresponds to the `m_num`.
noverlap: int
    Window overlap in samples. It relates to the `hop` increment by
    ``hop = npsereg - noverlap``.
symmetric_win: bool
    If ``True`` then a symmetric window is generated, else a periodic
    window is generated (default). Though symmetric windows seem for
    most applications to be more sensible, the default of a periodic
    windows was chosen to correspond to the default of `get_window`.
fft_mode : 'twosided', 'centered', 'onesided', 'onesided2X'
    Mode of FFT to be used (default 'onesided').
    See property `fft_mode` for details.
mfft: int | None
    Length of the FFT used, if a zero padded FFT is desired.
    If ``None`` (default), the length of the window `win` is used.
scale_to : 'magnitude', 'psd' | None
    If not ``None`` (default) the window function is scaled, so each
    STFT column represents  either a 'magnitude' or a power spectral
    density ('psd') spectrum. This parameter sets the property
    `scaling` to the same value. See method `scale_to` for details.
phase_shift : int | None
    If set, add a linear phase `phase_shift` / `mfft` * `f` to each
    frequency `f`. The default value 0 ensures that there is no phase
    shift on the zeroth slice (in which t=0 is centered). See property
    `phase_shift` for more details.

Examples
--------
The following instances ``SFT0`` and ``SFT1`` are equivalent:

>>> from scipy.signal import ShortTimeFFT, get_window
>>> nperseg = 9  # window length
>>> w = get_window(('gaussian', 2.), nperseg)
>>> fs = 128  # sampling frequency
>>> hop = 3  # increment of STFT time slice
>>> SFT0 = ShortTimeFFT(w, hop, fs=fs)
>>> SFT1 = ShortTimeFFT.from_window(('gaussian', 2.), fs, nperseg,
...                                 noverlap=nperseg-hop)

See Also
--------
scipy.signal.get_window: Return a window of a given length and type.
from_dual: Create instance using dual window.
ShortTimeFFT: Create instance using standard initializer.

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