def fmt_scale(prefix, scale):
    """
    format scale name

    :prefix: a string that is the beginning of the field name
    :scale: a scale value (0.25, 0.5, 1.0, 2.0)
    """

    scale_str = str(float(scale))
    scale_str.replace('.', '')
    return f'{prefix}_{scale_str}x'