# How to find the first Monday of a given month using NumPy?

Last Updated : 02 Dec, 2020

To find the first Monday of a given month, we are going to use the numpy module i.e the numpy.busday_offset() method in numpy module.

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.

#### Below are some programs which use numpy.busday_offset() method to get first Monday of a month:

Example #1:

In this example, we will find the first Monday of the month of May 2017.

## 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) `

Output:

`2017-05-01`

Example #2:

Here, we will find the first Monday of the month of February 2001.

## Python3

 `# 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) `

Output:

`2001-02-05`

Example #3:

Here, we will find the first Monday of the month of November 2020.

## Python3

 `# 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) `

Output:

`2001-11-02`

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