functions.py 文件源码

def butterworthFilter(data, wPass, wStop=None, gPass=2.0, gStop=20.0, order=1, dt=None, btype='low', bidir=True):
    """return data passed through bessel filter"""
    try:
        import scipy.signal
    except ImportError:
        raise Exception("butterworthFilter() requires the package scipy.signal.")

    if dt is None:
        try:
            tvals = data.xvals('Time')
            dt = (tvals[-1]-tvals[0]) / (len(tvals)-1)
        except:
            dt = 1.0

    if wStop is None:
        wStop = wPass * 2.0
    ord, Wn = scipy.signal.buttord(wPass*dt*2., wStop*dt*2., gPass, gStop)
    #print "butterworth ord %f   Wn %f   c %f   sc %f" % (ord, Wn, cutoff, stopCutoff)
    b,a = scipy.signal.butter(ord, Wn, btype=btype) 

    return applyFilter(data, b, a, bidir=bidir)