如何使用 NumPy 查找给定月份的第一个星期一？

要找到给定月份的第一个星期一，我们将使用numpy模块，即numpy模块中的numpy.busday_offset()方法。

Syntax: np.busday_offset(‘date’, 0, roll=’forward’, weekmask=’Mon’)

Parameters:

date: The array of dates to process.

offsets: The array of offsets, which is broadcast with dates.

roll:It takes the below values:

• raise means to raise an exception for an invalid day.
• nat means to return a NaT (not-a-time) for an invalid day.
• forward and following mean to take the first valid day later in time.
• backward and preceding mean to take the first valid day earlier in time.
• modifiedfollowing means to take the first valid day later in time unless it is across a Month boundary, in which case to take the first valid day earlier in time.
• modifiedpreceding means to take the first valid day earlier in time unless it is across a Month boundary, in which case to take the first valid day later in time.

weekmask: array indicating which of Monday through Sunday are valid days.

Returns (outarray of datetime64): An array with a shape from broadcasting dates and offsets together, containing the dates with offsets applied.

下面是一些使用numpy.busday_offset()方法获取一个月的第一个星期一的程序：

示例#1：

在此示例中，我们将找到 2017 年 5 月的第一个星期一。

Python3

# import module
import numpy
  
# input year and month
yearMonth = '2017-05'
  
# getting date of first monday
date = numpy.busday_offset(yearMonth, 0, 
                           roll='forward', 
                           weekmask='Mon')
  
# display date
print(date)

输出：

2017-05-01

示例#2：

在这里，我们将找到 2001 年 2 月的第一个星期一。

蟒蛇3

# import module
import numpy
  
# input year and month
yearMonth = '2001-02'
  
# getting date of first monday
date = numpy.busday_offset(yearMonth, 0,
                           roll='forward',
                           weekmask='Mon')
  
# display date
print(date)

输出：

2001-02-05

示例#3：

在这里，我们将找到 2020 年 11 月的第一个星期一。

蟒蛇3

# import module
import numpy
  
# input year and month
yearMonth = '2020-11'
  
# getting date of first monday
date = numpy.busday_offset(yearMonth, 0,
                           roll='forward',
                           weekmask='Mon')
  
# display date
print(date)

输出：

2001-11-02