line_waterfall()

trappist1_6_April_2017_analysis.py

def line_waterfall(compamp, width):
    arr = compamp - compamp.mean()  # set DC to zero
    
    # Hanning window for smoothing sharp time series start/end in freq. dom.
    arr = np.multiply(arr, np.hanning(compamp.shape[0]))
    arr = fft.fftshift(fft.fft(arr))  # FFT timeslice
    
    arr = np.abs(arr)  # magnitude of FFT
    arr = np.divide(arr, 0.5 * np.sqrt(arr.sum()))  # normalize to 0.5*sqrt(sum(abs(FFT)))
    arr = arr.reshape(width, arr.shape[0]/width).max(axis=(1))  # maxpool to width
    arr = np.clip(arr * 255., 0, 255)  # ready for grayscale image
    
    return arr.astype(np.uint8)

def stats(compamp):
    tmp = np.abs(compamp) ** 2
    return tmp.mean(), tmp.std()