Source code for sfs.tapering

"""Weights (tapering) for the driving function."""

# from scipy import signal
import numpy as np

[docs]def none(active): """No tapering window.""" return np.asarray(active, dtype=np.float64)
[docs]def kaiser(active): """Kaiser tapering window.""" idx = _windowidx(active) # compute coefficients window = np.zeros(active.shape) window[idx] = np.kaiser(len(idx), 2) return window
[docs]def tukey(active, alpha): """Tukey tapering window.""" idx = _windowidx(active) # alpha out of limits if alpha <= 0 or alpha >= 1: return none(active) # design Tukey window x = np.linspace(0, 1, len(idx)+2) w = np.ones(x.shape) first_condition = x < alpha/2 w[first_condition] = 0.5 * (1 + np.cos(2*np.pi/alpha * (x[first_condition] - alpha/2))) third_condition = x >= (1 - alpha/2) w[third_condition] = 0.5 * (1 + np.cos(2*np.pi/alpha * (x[third_condition] - 1 + alpha/2))) # fit window into tapering function window = np.zeros(active.shape) window[idx] = w[1:-1] return window
def _windowidx(active): """Returns list of connected indices for window function.""" active = np.asarray(active, dtype=np.float64) # find index were active loudspeakers begin (works for connected contours) if (active == 1 and active[-1] == 0) or np.all(active): a0 = 0 else: a0 = np.argmax(np.diff(active)) + 1 # shift generic index vector to get a connected list of indices idx = np.roll(np.arange(len(active)), -a0) # remove indices of inactive secondary sources idx = idx[0:len(np.squeeze(np.where(active == 1)))] return idx