HelperFunctions.py 文件源码

def fwhm(x, y, k=10, ret_roots=False):
    """
    Determine full-with-half-maximum of a peaked set of points, x and y.

    Assumes that there is only one peak present in the dataset.  The function
    uses a spline interpolation with smoothing parameter k ('s' in scipy.interpolate.UnivariateSpline).

    If ret_roots=True, return the x-locations at half maximum instead of just
    the distance between them.
    """


    class NoPeaksFound(Exception):
        pass

    half_max = np.max(y) / 2.0
    s = UnivariateSpline(x, y - half_max, s=k)
    roots = s.roots()

    if len(roots) > 2:
        # Multiple peaks. Use the two that straddle the maximum value
        maxvel = x[np.argmax(y)]
        left_idx = np.argmin(maxvel - roots)
        right_idx = np.argmin(roots - maxvel)
        roots = np.array((roots[left_idx], roots[right_idx]))
    elif len(roots) < 2:
        raise NoPeaksFound("No proper peaks were found in the data set; likely "
                           "the dataset is flat (e.g. all zeros).")
    if ret_roots:
        return roots[0], roots[1]

    return abs(roots[1] - roots[0])