Add norm on function

[mrschweizer]

def substract_background(x, y, dim=None, f_max=2, f_min = None):
    """
    Use a reference measurement to substract the background. Background is renormalized to match the intensity of the
    main measurement in the specified interval and then substracted from the main.
    :param x: xarray object
    :param y: xarray object (background)
    :param name: Name of the Frequency coordinate axis along which the frequency is to be selected
    :param f_min: specifies the minimum of the frequency area over which is to be normalized
    :param f_max: specifies the maximum of the frequency area over which is to be normalized
    :return: x without background, xarray object
    """

    norm = x.sel({dim: slice(f_min, f_max)}).sum(dim)
    return x - y/y.sel({dim: slice(f_min, f_max)}).sum(dim)*norm

[mrschweizer]

resolved dbf3798