Question

我需要知道如何遍历列表并找到最接近限速的速度。如此反复遍历速度列表，每次都看一下差异。

到目前为止我所拥有的：

def find_nearest_speed(recorded_speeds, speed_limit):
"""Finds the closest recorded speed when compared to the speed limit."""
closest = abs(speed_data[0] - speed_limit)
for current_element in speed_data:
    speed_difference = abs(current_element - speed_limit)
    if speed_difference < abs(closest - speed_limit):
        closest = current_element
        return closest

max_speed = 30 
speed_data = [24, 25, 27, 28, 31, 35]           
closest_speed = (find_nearest_speed(speed_data, max_speed))
print("The closest recorded speed was {} Km/h.".format(closest_speed))

我得到的是

 The closest recorded speed was 24 Km/h.

我应该得到的：

 The closest recorded speed was 31 Km/h.

Answer 1

您可以使用min：

max_speed = 30
speed_data = [24, 25, 27, 28, 31, 35]
closest_speed = min(speed_data, key=lambda x: abs(x - max_speed))
print("The closest recorded speed was {} Km/h.".format(closest_speed))

输出

The closest recorded speed was 31 Km/h.

Answer 2

这是您应该拥有的：

def find_nearest_speed(recorded_speeds, speed_limit):
"""Finds the closest recorded speed when compared to the speed limit."""
    closest = float('inf')
    for current_element in speed_data:
        speed_difference = abs(current_element - speed_limit)
        if speed_difference < abs(closest - speed_limit):
            closest = current_element
    return closest if len(recorded_speeds) > 0 else None

唯一的变化是最初closest = float('inf')

Answer 3

如果在return语句“内部”使用if语句，则只要满足条件speed_difference < abs(closest - speed_limit)为true，它将立即返回您的代码用于列表的第一个元素。

因此，您需要在return语句之前删除缩进，以便它在循环结束之前返回结果。

另一个要注意的是，语句closest = abs(speed_data[0] - speed_limit)是错误的，因为您要为closest变量分配list元素和speed_limit之间的差异，但是要查看函数代码您应该为它分配一个列表元素：closest = speed_data[0]。

def find_nearest_speed(recorded_speeds, speed_limit):
    """Finds the closest recorded speed when compared to the speed limit."""
    closest = speed_data[0] # Sets the closest as the list's first element
    for current_element in speed_data:
        speed_difference = abs(current_element - speed_limit)
        if speed_difference < abs(closest - speed_limit):
            closest = current_element
    return closest

max_speed = 30 
speed_data = [24, 25, 27, 28, 31, 35]           
closest_speed = (find_nearest_speed(speed_data, max_speed))
print("The closest recorded speed was {} Km/h.".format(closest_speed))

在数字列表中查找最接近的记录速度[python]

3 个答案: