Finding the Number of Weekdays of a Given Month in NumPy

NumPy is a powerful Python library for numerical computing and data analysis. When working with date calculations, you often need to count weekdays (business days) within a specific month, excluding weekends and holidays.

You can install NumPy using pip ?

pip install numpy

NumPy's busday_count() function calculates the number of business days (Monday to Friday) between two specific dates.

Syntax

numpy.busday_count(startdate, enddate, weekmask='1111100', holidays=None)

Parameters

• startdate Start date (inclusive) in "YYYY-MM-DD" format

• enddate End date (exclusive) in "YYYY-MM-DD" format

• weekmask Optional string defining valid weekdays (default: Monday-Friday)

• holidays Optional array of holiday dates to exclude

Return Value

Returns an integer representing the number of valid business days.

Example 1: Basic Weekday Count

Calculate weekdays in February 2023 ?

import numpy as np

# Count weekdays in February 2023
num_days = np.busday_count('2023-02-01', '2023-03-01')

print(f"There are {num_days} weekdays in February 2023")

There are 20 weekdays in February 2023

Example 2: Leap Year Calculation

Calculate weekdays in February 2024 (leap year) with explicit weekmask ?

import numpy as np

# Count weekdays in February 2024 (leap year)
num_days = np.busday_count('2024-02-01', '2024-03-01', 
                          weekmask='Mon Tue Wed Thu Fri')

print(f"There are {num_days} weekdays in February 2024")

There are 21 weekdays in February 2024

Example 3: Excluding Holidays

Count weekdays while excluding national holidays ?

import numpy as np

# Define holidays in January 2023
holidays = ['2023-01-01', '2023-01-26']

# Count weekdays excluding holidays
num_days = np.busday_count('2023-01-01', '2023-02-01', holidays=holidays)

print(f"Weekdays in January 2023 excluding holidays: {num_days}")

# Compare with total weekdays (no holidays excluded)
total_weekdays = np.busday_count('2023-01-01', '2023-02-01')
print(f"Total weekdays without excluding holidays: {total_weekdays}")

Weekdays in January 2023 excluding holidays: 21
Total weekdays without excluding holidays: 22

How It Works

The busday_count() function only excludes holidays that fall on weekdays. Since January 1st, 2023 was a Sunday, it wasn't counted as a weekday anyway. Only January 26th (Republic Day, which fell on a Thursday) was excluded from the count.

Custom Weekmask Example

Define custom working days (e.g., Tuesday to Saturday) ?

import numpy as np

# Custom weekmask: Tuesday to Saturday
custom_days = np.busday_count('2023-03-01', '2023-04-01', 
                             weekmask='Tue Wed Thu Fri Sat')

print(f"Tuesday-Saturday working days in March 2023: {custom_days}")

Tuesday-Saturday working days in March 2023: 22

Comparison of Methods

Conclusion

NumPy's busday_count() function efficiently calculates weekdays between dates, making it invaluable for business applications like payroll, project management, and financial calculations. It handles leap years, holidays, and custom work schedules seamlessly.