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, average='mean', 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
 instinstance of
Epochs
orRaw
orEvoked
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 zeropadded ifn_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). projbool
Apply SSP projection vectors. If inst is ndarray this is not used.
 n_jobs
int
The number of jobs to run in parallel (default 1). Requires the joblib package.
 reject_by_annotationbool
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.
 average
str
None
How to average the segments. If
mean
(default), calculate the arithmetic mean. Ifmedian
, calculate the median, corrected for its bias relative to the mean. IfNone
, returns the unaggregated segments.New in version 0.19.0.
 verbosebool,
str
,int
, orNone
If not None, override default verbose level (see
mne.verbose()
and Logging documentation for more).
 instinstance of
 Returns
 psds
ndarray
, shape (…, n_freqs) or (…, n_freqs, n_segments) The power spectral densities. If
average='mean
oraverage='median'
and input is of type Raw or Evoked, then psds will be of shape (n_channels, n_freqs); if input is of type Epochs, then psds will be of shape (n_epochs, n_channels, n_freqs). Ifaverage=None
, the returned array will have an additional dimension corresponding to the unaggregated segments. freqs
ndarray
, shape (n_freqs,) The frequencies.
 psds
Notes
New in version 0.12.0.