根据python的月份查找日期

Question

在给定年份，月份和星期编号（第1，第2，第3等）的情况下，有没有办法查找特定周内的日期范围？我已经看到很多关于如何查找基于特定日期的星期数的答案，但我正在尝试根据星期数找到日期。举例来说，（2013，9，“星期四”，“第3”）给出了结果（2013,9,19）。

这里是我到目前为止的代码（仅适用于在“teenth”结束日期）：

from datetime import date 

def meetupday(year, month, weekday, word): 
    weekday_dic = {"Monday": 0, "Tuesday": 1, "Wednesday": 2, "Thursday": 3, 
       "Friday": 4, "Saturday": 5, "Sunday": 6} 
    week_of_the_month = {"1st": 1, "2nd": 2, "3rd": 3, "4th": 4, "last": 5} 
    if word == "teenth": 
     for day in xrange(13, 20): 
     if weekday_dic[weekday] == date(year, month, day).weekday(): 
      return year, month, day 
    else: 
    for date in xrange(1, amount_of_days+1): 
     date_data = datetime.date(year, month, date).isocalendar() 
     if date_data[2] == weekday_dic[weekday]+1: 
      return year, month, week_of_the_month[word] 

这是exercism.io的聚会问题。

Answer 1

我的解决方案基于您给定的数据的日期将是类似的东西

from datetime import datetime, timedelta  
weekday_dic = {"Monday": 0, "Tuesday": 1, "Wednesday": 2, "Thursday": 3, 
        "Friday": 4, "Saturday": 5, "Sunday": 6} 
week_of_the_month = {"1st": 1, "2nd": 2, "3rd": 3, "4th": 4, "last": 5} 

start_first_week = first_sunday = datetime(year, month, 1) 
while start_first_week.weekday() != weekday_dic[weekday]: 
    start_first_week += timedelta(days=1) 

start_first_week += timedelta(days=(week_of_the_month[word] - 1) * 7) 

我希望帮助你一点

Answer 2

一个快速的问题，我发现了达达主义的解决方案是，当我试图计算每年美国阵亡将士纪念日的日期（5月的最后一个星期一）。我会得到2018-06-04。根据我的参数，这不是正确的月份。如果输出月份与输入不匹配，我添加了一个快速修复，只需要减去7天。我不确定底层问题是什么。现在返回正确答案：2018-05-28。

from datetime import datetime, timedelta  
weekday_dic = {"Monday": 0, "Tuesday": 1, "Wednesday": 2, "Thursday": 3, 
         "Friday": 4, "Saturday": 5, "Sunday": 6} 
week_of_the_month = {"1st": 1, "2nd": 2, "3rd": 3, "4th": 4, "last": 5} 

start_first_week = first_sunday = datetime(year, month, 1) 
while start_first_week.weekday() != weekday_dic[weekday]: 
    start_first_week += timedelta(days=1) 

start_first_week += timedelta(days=(week_of_the_month[word] - 1) * 7) 
if start_first_week.month != month: 
    start_first_week += datetime.delta(days=-7)