Filtering

Filtering BeForRecord data

befordata.filtering.filtfilt(b, a, rec[, ...])	Applies a digital filter forward and backward to each force data column in a BeForRecord.
befordata.filtering.lowpass_filter(rec, ...)	Convenience function to apply a lowpass Butterworth filter to the force data in a BeForRecord.

befordata.filtering

filtfilt(b, a, rec, inplace=False, **kwargs)

Applies a digital filter forward and backward to each force data column in a BeForRecord.

This function basically wraps scipy.signal.filtfilt to provide a zero-phase filtering for all force columns in every session of the provided BeForRecord.

Return type:

BeForRecord

Parameters:

b(N,) array_like

The numerator coefficient vector of the filter.

a(N,) array_like

The denominator coefficient vector of the filter. If a[0] is not 1, then both a and b are normalized by a[0].

recBeForRecord

The BeForRecord instance containing the data to filter.

inplacebool, optional (default: False)

If True, perform filtering in place and modify the original data.

**kwargs

Additional keyword arguments passed to scipy.signal.filtfilt.

Notes

Documentation of scipy.signal.filtfilt: https://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.filtfilt.html

Examples

>>> from scipy import signal
>>> from befordata import BeForRecord, filtering
>>> rec = BeForRecord(...)  # Create a BeForRecord instance
>>> b, a = signal.butter(N=4, Wn=30, fs=1000, btype='low')
>>> filtered = filtering.filtfilt(b, a, rec)

lowpass_filter(rec, cutoff, order)

Convenience function to apply a lowpass Butterworth filter to the force data in a BeForRecord.

This function filters each force data column in every session of the provided BeForRecord using a zero-phase Butterworth lowpass filter. Optionally, the data can be centred (subtracting the first sample) before filtering to reduce edge artifacts.

Returns a BeForRecord instance with the filtered force data. No inplace modification is performed to preserve the original data.

Return type:

BeForRecord

Parameters:

recBeForRecord

cutofffloat

The cutoff frequency of the lowpass filter (in Hz).

orderint

The order of the Butterworth filter.

center_databool, optional (default: True)

If True, center the data by subtracting the first sample before filtering.

Notes

Filtering is performed using scipy.signal.butter and scipy.signal.filtfilt for zero-phase filtering. See the SciPy documentation for more details: https://docs.scipy.org/doc/scipy/reference/signal.html

Examples

>>> from befordata import BeForRecord, filtering
>>> rec = BeForRecord(...)  # Create a BeForRecord instance
>>> filtered = filtering.lowpass_filter(rec, cutoff=30, order=4)