util.py 文件源码

def compute_scale(
        min_, max_, logarithmic, order_min,
        min_scale, max_scale):
    """Compute an optimal scale between min and max"""
    if min_ == 0 and max_ == 0:
        return [0]
    if max_ - min_ == 0:
        return [min_]
    if logarithmic:
        log_scale = compute_logarithmic_scale(
            min_, max_, min_scale, max_scale)
        if log_scale:
            return log_scale
            # else we fallback to normal scalling

    order = round(log10(max(abs(min_), abs(max_)))) - 1
    if order_min is not None and order < order_min:
        order = order_min
    else:
        while ((max_ - min_) / (10 ** order) < min_scale and
               (order_min is None or order > order_min)):
            order -= 1
    step = float(10 ** order)
    while (max_ - min_) / step > max_scale:
        step *= 2.
    positions = []
    position = round_to_scale(min_, step)
    while position < (max_ + step):
        rounded = round_to_scale(position, step)
        if min_ <= rounded <= max_:
            if rounded not in positions:
                positions.append(rounded)
        position += step
    if len(positions) < 2:
        return [min_, max_]
    return positions