This is my current code for a tax calculator based on age. I think that it would be easier to update in the future if I used data structures when calculating the brackets. Could someone help me make sense of this?
while True: #Loop the whole program
from datetime import datetime, date #Get the Age of from user input
print("Please enter your date of birth (dd mm yyyy)")
date_of_birth = datetime.strptime(input("--->"), "%d %m %Y")
def calculate_age(born):
today = date.today()
return today.year - born.year - ((today.month, today.day) < (born.month, born.day))
age = calculate_age(date_of_birth)
print("You are " ,int(age), " years old.")
#Get the Salary from user input
def get_salary():
while True:
try:
salary = int(input("Please enter your salary: "))
except ValueError:
print("You need to enter a number ")
else:
break
return salary
#Calculate the Amount that needs to be paid, using if,elif,else
def contribution(age):
if age <= 35:
tax = (salary * 0.20)
elif 36 <= age <= 50:
tax = (salary * 0.20)
elif 51 <= age <= 55:
tax = (salary * 0.185)
elif 56 <= age <= 60:
tax = (salary * 0.13)
elif 61 <= age <= 65:
tax = (salary * 0.075)
else:
tax = (salary * 0.05)
return tax
#Print the amount
if __name__ == "__main__": # It's as if the interpreter inserts this at the top of your module when run as the main program.
salary = get_salary() #get salary from get_salary()
tax = contribution(age) #calculate the tax
print("you have to pay", tax, " every month ")
while True:
answer = str(input("Do you need to do another calculation? (y/n): "))
if answer in ("y", "n"):
break
print ("invalid input.")
if answer == "y":
continue
else:
print("Thank you for using this Calculator, Goodbye")
break
So the code that I’m assuming that I need to change is:
#Calculate the Amount that needs to be paid, using if,elif,else
def contribution(age):
if age <= 35:
tax = (salary * 0.20)
elif 36 <= age <= 50:
tax = (salary * 0.20)
elif 51 <= age <= 55:
tax = (salary * 0.185)
elif 56 <= age <= 60:
tax = (salary * 0.13)
elif 61 <= age <= 65:
tax = (salary * 0.075)
else:
tax = (salary * 0.05)
return tax
Also, I’m trying to learn so could you explain by putting #comments into the code :) Thank you!
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Answer
1. Rewrite the code structure
First of all, I think most programmers do like to put function blocks all together and leave the main logic as clean/short as possible to improve readability. Therefore the ‘code structure’ like this could be hard to maintain or update in the future.
while True: #Loop the whole program
from datetime import datetime, date #Get the Age of from user input
def calculate_age(born): ...
def get_salary(): ...
def contribution(age): ...
if __name__ == "__main__":
# main logic
...
So this kind of structure is really weird, plus you have lots of variables (date_of_birth, age) declared between functions. Would be hard to do the update/maintenance.
If I were you, I’d firstly revise the code like this way
from datetime import datetime, date #Get the Age of from user input
def calculate_age(born): ...
def get_salary(): ...
def contribution(age): ...
if __name__ == "__main__": # It's as if the interpreter inserts this at the top of your module when run as the main program.
program_continue = 'y'
while program_continue.upper() in ['Y', 'YES']:
print("Please enter your date of birth (dd mm yyyy)")
date_of_birth = datetime.strptime(input("--->"), "%d %m %Y")
age = calculate_age(date_of_birth)
print("You are " ,int(age), " years old.")
salary = get_salary() #get salary from get_salary()
tax = contribution(age) #calculate the tax
print("you have to pay", tax, " every month ")
program_continue = str(input("Do you need to do another calculation? (y/n): "))
print("Thank you for using this Calculator, Goodbye")
2. Introduce data structure? or class?
Honestly I don’t quite understand what do you mean by “using data structure”, so I guess make a “class” is the one you wish. Then you have to consider some points:
- what should be the attributes for this class? dob, salary, anything else?
- what will you expand in the future? name? gender? contact_info? handicapped or not?
Whatever, we just create a class with dob and salary for now.
class Person(object):
def __init__(self, dob, salary):
"""
input dob and salary only, age and tax will be calculated then
"""
self.dob = dob
self.salary = salary
self.age = self.calculate_age()
self.tax = self.contribution()
def calculate_age(self):
today = date.today()
return today.year - self.dob.year - ((today.month, today.day) < (self.dob.month, self.dob.day))
def contribution(self):
if self.age <= 35:
tax = (self.salary * 0.20)
elif 36 <= self.age <= 50:
tax = (self.salary * 0.20)
elif 51 <= self.age <= 55:
tax = (self.salary * 0.185)
elif 56 <= self.age <= 60:
tax = (self.salary * 0.13)
elif 61 <= self.age <= 65:
tax = (self.salary * 0.075)
else:
tax = (self.salary * 0.05)
return tax
So once you create a variable in the class Person, you can access the age, salary, tax via .age, .salary, .tax.
Please notice that I did not put the function get_salary() into the class since it’s a function for “asking user’s salary” and has nothing to do with the attribute.
The main logic can be rewritten to:
if __name__ == "__main__": # It's as if the interpreter inserts this at the top of your module when run as the main program.
program_continue = 'y'
while program_continue.upper() in ['Y', 'YES']:
print("Please enter your date of birth (dd mm yyyy)")
date_of_birth = datetime.strptime(input("--->"), "%d %m %Y")
salary = get_salary() #get salary from get_salary()
##### THESE ARE THE CHANGES START
person_obj = Person(date_of_birth, salary)
print("You are ", int(person_obj.age), " years old.")
print("you have to pay", int(person_obj.tax), " every month ")
##### THESE ARE THE CHANGES END
program_continue = str(input("Do you need to do another calculation? (y/n): "))
print("Thank you for using this Calculator, Goodbye")
3. Future expansion
Let’s say if I want to add name as an attribute now. All I have to do is to modify the Person class. Should be easier for you to update in the future.