计算列表的平均时间产生错误答案

【问题标题】：calculate average time of list yields error计算列表的平均时间产生错误
【发布时间】：2017-10-06 13:10:42
【问题描述】：

我正在尝试使用来自this 线程的代码从列表中计算平均时间。所有其他代码建议都不适合我，因为它们考虑的是持续时间而不是时间。

import datetime
import math
import numpy

def datetime_to_radians(x):
    # radians are calculated using a 24-hour circle, not 12-hour, starting at north and moving clockwise
    time_of_day = x.time()
    seconds_from_midnight = 3600 * time_of_day.hour + 60 * time_of_day.minute + time_of_day.second
    radians = float(seconds_from_midnight) / float(12 * 60 * 60) * 2.0 * math.pi
    return radians

def average_angle(angles):
    # angles measured in radians
    x_sum = numpy.sum([math.sin(x) for x in angles])
    y_sum = numpy.sum([math.cos(x) for x in angles])
    x_mean = x_sum / float(len(angles))
    y_mean = y_sum / float(len(angles))
    return numpy.arctan2(x_mean, y_mean)

def radians_to_time_of_day(x):
    # radians are measured clockwise from north and represent time in a 24-hour circle
    seconds_from_midnight = int(float(x) / (2.0 * math.pi) * 12.0 * 60.0 * 60.0)
    hour = seconds_from_midnight / 3600
    minute = (seconds_from_midnight % 3600) / 60
    second = seconds_from_midnight % 60
    return datetime.time(hour, minute, second)

def average_times_of_day(x):
    # input datetime.datetime array and output datetime.time value
    angles = [datetime_to_radians(y) for y in x]
    avg_angle = average_angle(angles)
    return radians_to_time_of_day(avg_angle)

average_times_of_day([datetime.datetime(2017, 6, 9, 0, 10), datetime.datetime(2017, 6, 9, 0, 20)])
# datetime.time(0, 15)

average_times_of_day([datetime.datetime(2017, 6, 9, 23, 50), datetime.datetime(2017, 6, 9, 0, 10)])
# datetime.time(0, 0)

我收到以下错误：

TypeError: integer argument expected, got float

有人可以帮忙吗？

【问题讨论】：

运行代码并获得结果datetime.time(0, 15) 和datetime.time(0, 0) 没有问题。你可以重启你的机器再试一次。
还是一样。我得到了 Python 3.6.2 (Anaconda)。有什么想法吗？
在下面查看我的回复。
请阅读"What should I do when someone answers my question?"。

标签： python

【解决方案1】：

这是另一种解决方案，它可以处理仅考虑小时和分钟的日期时间对象列表：

from cmath import phase
from cmath import rect
import datetime
from math import degrees
from math import radians

dfList = ([datetime.datetime(2017, 9, 15, 8, 8),
           datetime.datetime(2017, 9, 14, 8, 5),
           datetime.datetime(2017, 9, 13, 6, 56),
           datetime.datetime(2017, 12, 9, 6, 14),
           datetime.datetime(2017, 11, 9, 6, 42)])

dfList = [item.strftime("%H:%M") for item in dfList]


def mean_angle(deg):
    return degrees(phase(sum(rect(1, radians(d)) for d in deg) / len(deg)))


def mean_time(times):
    t = (time.split(':') for time in times)
    seconds = ((int(m) * 60 + int(h) * 3600)
               for h, m in t)
    day = 24 * 60 * 60
    to_angles = [s * 360. / day for s in seconds]
    mean_as_angle = mean_angle(to_angles)
    mean_seconds = mean_as_angle * day / 360.
    if mean_seconds < 0:
        mean_seconds += day
    h, m = divmod(mean_seconds, 3600)
    m, s = divmod(m, 60)
    return '%02i:%02i' % (h, m)


print(mean_time(dfList))

【讨论】：

【解决方案2】：

在 Python 3 中，/ 执行真（浮点）除法，即使两个操作数都是整数。

改用//

def radians_to_time_of_day(x):
    # radians are measured clockwise from north and represent time in a 24-hour circle
    seconds_from_midnight = int(float(x) / (2.0 * math.pi) * 12.0 * 60.0 * 60.0)
    hour = seconds_from_midnight // 3600
    minute = (seconds_from_midnight % 3600) // 60
    second = seconds_from_midnight % 60
    return datetime.time(hour, minute, second)

【讨论】：

【解决方案3】：

您的代码在 Python 2.7 中运行良好，但在 Python 3.6 中运行良好。

错误出现在第 26 行，return datetime.time(hour, minute, second)。

将hour、minute和second的值转换为int()后，就可以正常工作了。

def radians_to_time_of_day(x):
    # radians are measured clockwise from north and represent time in a 24-hour circle
    seconds_from_midnight = int(float(x) / (2.0 * math.pi) * 12.0 * 60.0 * 60.0)
    hour = int(seconds_from_midnight / 3600)
    minute = int((seconds_from_midnight % 3600) / 60)
    second = int(seconds_from_midnight % 60)
    return datetime.time(hour, minute, second)

【讨论】：