This documentation is for development version 0.18.dev0.

mne.time_frequency.psd_welch

mne.time_frequency.psd_welch(inst, fmin=0, fmax=inf, tmin=None, tmax=None, n_fft=256, n_overlap=0, n_per_seg=None, picks=None, proj=False, n_jobs=1, reject_by_annotation=True, verbose=None)[source]

Compute the power spectral density (PSD) using Welch’s method.

Calculates periodograms for a sliding window over the time dimension, then averages them together for each channel/epoch.

Parameters:
inst : instance of Epochs or Raw or Evoked

The data for PSD calculation

fmin : float

Min frequency of interest

fmax : float

Max frequency of interest

tmin : float | None

Min time of interest

tmax : float | None

Max time of interest

n_fft : int

The length of FFT used, must be >= n_per_seg (default: 256). The segments will be zero-padded if n_fft > n_per_seg. If n_per_seg is None, n_fft must be >= number of time points in the data.

n_overlap : int

The number of points of overlap between segments. Will be adjusted to be <= n_per_seg. The default value is 0.

n_per_seg : int | None

Length of each Welch segment (windowed with a Hamming window). Defaults to None, which sets n_per_seg equal to n_fft.

picks : str | list | slice | None

Channels to include. Slices and lists of integers will be interpreted as channel indices. In lists, channel type strings (e.g., ['meg', 'eeg']) will pick channels of those types, channel name strings (e.g., ['MEG0111', 'MEG2623'] will pick the given channels. Can also be the string values “all” to pick all channels, or “data” to pick data channels. None (default) will pick good data channels(excluding reference MEG channels).

proj : bool

Apply SSP projection vectors. If inst is ndarray this is not used.

n_jobs : int

Number of CPUs to use in the computation.

reject_by_annotation : bool

Whether to omit bad segments from the data while computing the PSD. If True, annotated segments with a description that starts with ‘bad’ are omitted. Has no effect if inst is an Epochs or Evoked object. Defaults to True.

New in version 0.15.0.

verbose : bool, str, int, or None

If not None, override default verbose level (see mne.verbose() and Logging documentation for more).

Returns:
psds : ndarray, shape (…, n_freqs)

The power spectral densities. If input is of type Raw, then psds will be shape (n_channels, n_freqs), if input is type Epochs then psds will be shape (n_epochs, n_channels, n_freqs).

freqs : ndarray, shape (n_freqs,)

The frequencies.

Notes

New in version 0.12.0.