We Keep Coding

amortization/loan table without using pandas

What would be the best way to create a monthly amortization table without using pandas? Say I am given the amount of the loan, the annual interest rate, and the duration in years. How can I make a table that gives the period, beginning balance, principle, interest, and then the ending balance? And then the amount in the ending be equal to 0.
For example if I had a 150,000 loan, 10% rate, and a duration of 25 years (300 months), I don't want to use user input on this though
Formatted something like this (output will be super long I know):
month begin bal. interest principal end bal.
1 xxxx xxxx xxxx xxxx
.
.
I can attach what I have started on, but I know it is horrible lol, I am horrible with formulas/tables in Python it just does not click with me so I am struggling. Anything will help, thanks!
#p = r(pv)/(1-(1+r)**-n)
loan = 150000
rate = 10/100 #10%
term = 25 #25 years
for i in range(loanTerm):
print("month. begin bal. interest. principal. ending bal")
beginB = loanAmt
pv = loan
r = rate/100
n = term*12
p = r(pv)/(1-(1+r)**-n)
^ I know that is a very sad attempt with many errors I am embarrassed LOL just don't even know where to start. Let me know if there is anything I need to clarify!

Well, to start out with, you compute all of your constants before the loop.
#p = r(pv)/(1-(1+r)**-n)
loan = 150000
rate = 10/100 #10%
term = 25
mo_rate = rate/12
mo_term = term*12
factor = (1 + mo_rate) ** mo_term
pmt = round(loan * (mo_rate * factor) / (factor - 1), 2)
print( "Payments are", pmt, "per month")
balance = loan
print( "month\tbal\tint\tprin\tending" )
for i in range(mo_term):
interest = balance * mo_rate
ending = balance + interest - pmt
print( f"{i}\t{balance:.2f}\t{interest:.2f}\t{pmt-interest:.2f}\t{ending:.2f}" )
balance = ending

How do you round a string in Python?

I am new to Python and a student, my college has chosen the worst book on earth for our course. I cannot find examples of any concepts, so I apologize in advance as I know these concepts are very basic. I hope you can help me.
I need to know how to use the round feature in a string. I find examples but they do not show the string, just simple numbers.
Here is what we are supposed to get as an output:
Enter the gross income: 12345.67
Enter the number of dependents: 1
The income tax is $-130.87 <---- this is what we are supposed to figure out
Here is the coding we are given to alter:
TAX_RATE = 0.20
STANDARD_DEDUCTION = 10000.0
DEPENDENT_DEDUCTION = 3000.0
# Request the inputs
grossIncome = float(input("Enter the gross income: "))
numDependents = int(input("Enter the number of dependents: "))
# Compute the income tax
taxableIncome = grossIncome - STANDARD_DEDUCTION - \
DEPENDENT_DEDUCTION * numDependents
incomeTax = taxableIncome * TAX_RATE
# Display the income tax
print("The income tax is $" + str(incomeTax))
As I do not have an NUMBER to plug into the formula - I have to figure out how to use "incomeTax" - I have no idea how to do this. THe book doesnt explain it. Help?

You can use format strings:
print("The income tax is ${:.2f}".format(incomeTax))
If you are using Python 3.6+, you can also use f-strings:
print(f"The income tax is ${incomeTax:.2f}")

You can round just before making it a string:
print("The income tax is $" + str(round(incomeTax,2)))
Output:
Enter the gross income: 12345.67
Enter the number of dependents: 1
The income tax is $-130.87

Im a student as well, with the same dumb book and HW.
I tried the above
str(round(incomeTax,2))
and it didn’t work. Maybe I typed something wrong. After playing around I found this to work
# Display the income tax
incomeTax = round(incomeTax,2)
print(“The income tax is $” + str(incomeTax))
I hope this helps some other poor soul searching the web for an answer!

Working with commas in output

I'm in an intro programming class and am lost. We've had several labs that required knowledge that we haven't been taught but I've managed to find out what I need on google (as nobody responds to the class message board) but this one has me pretty frustrated. I'll include a pastebin link here: https://pastebin.com/6JBD6NNA
`principal = input()
print('Enter the Principal Value of your investment: $', float(principal))
time = input()
print('\nEnter the Time(in years) you plan to save your investment: ', int(time))
rate = input()
print('\nEnter the Rate (2% = 0.02) you will collect on your investment: ', float(rate))
interest = (float(principal) * float(rate)) * int(time)
final_value = float(principal) + float(interest)
print('\nThe Final Value of your investment will be: $%.2f' % final_value)`
So I need the output of the dollar amounts to have a comma ($27,500.00) but I have no idea how to do this. I've seen a couple of solutions on this site and others but I can't get them to work. PLEASE can someone help me?

In Python 2.7 or above, you can use
print('The Final Value of your investment will be: ${:,.2f}'.format(final_value))
This is documented in PEP 378.
Source: Python Add Comma Into Number String

Here is a working example:
principal = float(input('Enter the Principal Value of your investment: $'))
time = int(input('\nEnter the Time(in years) you plan to save your investment: '))
rate = float(input('\nEnter the Rate (2% = 0.02) you will collect on your investment: '))
interest = principal * rate * time
final_value = principal + interest
print('The Final Value of your investment will be: ${:,.2f}'.format(final_value))

Your last line should be:
print ("\nThe Final Value of your investment will be: ${:,.2f}".format(final_value))

Loan calculator program

So far I have been coding this all week trying to get it to work.
It should come out as this:
Please enter Amount that you would like to borrow(£): 4000
Please enter Duration of the loan(Years):2
Please enter the interest rate (%):6
The total amount of interest for 2 (years) is: £480.00
The total amount of the period for 2 (years) is £4480.00
You will pay £186.67 per month for 24 months.
Do you wish to calculate a new loan payment(Y or N)
Code:
monthlypayment = 0 #Variable
loanamount = 0 #Variable
interestrate = 0 #Variable
numberofpayments = 0 #Variable
loandurationinyears = 0 #Variable
loanamount = input("Please enter the amount that you would like to borrow(£) ")
loandurationinyears = input("How many years will it take you to pay off the loan? ")
interestrate = input("What is the interest rate on the loan? ")
#Convert the strings into floating numbers
loandurationinyears = float(loandurationinyears)
loanamount = float(loanamount)
interestrate = float(interestrate)
#Since payments are once per month, number of payments is number of years for the loan
numberofpayments = loandurationinyears*12
#calculate the monthly payment based on the formula
monthlypayment = (loanamount * interestrate * (1+ interestrate)
* numberofpayments / ((1 + interestrate) * numberofpayments -1))
#Result to the program
print("Your monthly payment will be " + str(monthlypayment))

looks to me like the only thing you're missing in the code above from what you described is a while loop. This will allow your program to calculate the loan and run the program over and over again until the user inputs no, in which case the program exits. all what you have to do is:
YorNo = input("Do you wish to calculate a loan payment")
YorNo.Title()
while YorNo != "n":
#Your code goes here
YorNo = input("Do you wish to calculate a loan payment")
YorNo.Title()
print("Thank you for using the program")
In case you dont understand this, baisically, you type the first 3 lines just before your code. Then you leave an indentation and type your code after them. Once your done, you type in the 3rd and 4th line. Then, simply go back that indentation (to show the program that this isnt part of the loop.) If im not mistaken, the result of this will be:
You will be asked wether you want to calculate a loan
If you answer "y" your code will run and the loan will be calculated and printed to the user
Then you will be asked again. The above will repeat until you input "n"
the N cant be capitalised

Comparing Loans in Python

I am doing an assignment for my Python class. I almost figured it out but my output is just a little bit different with the one showed in the original problem. When interest rate is 5.125%, I have a Monthly Payment for 189.29, but the output from the problem is 188.28. The original number without format is 189.286. I guess maybe in the finance system, they just simply cut the decimals instead of using "round". I am not sure if there is any way to do that in Python. Here is the problem.
Write a program that lets the user enter the loan amount and loan period in number of years and displays the monthly and total payments for each interest rate starting from 5% to 8%, with an increment of 1/8.
Input:
Loan Amount: 10000
Number of Years: 5
Output:
Interest Rate Monthly Payment Total Payment
5.000% 188.71 11322.74
5.125% 189.29 11357.13
...
7.875% 202.17 12129.97
8.000% 202.76 12165.84
Code:
LoanAmount = float(input("Loan Amount:"))
NumOfYears = float(input("Number of Years:"))
AnnualRate = float(5.0)
print("\nInterest Rate\t" + "Monthly Payment\t" + "Total Payment")
while (AnnualRate <= 8.0):
MonthlyRate = float(AnnualRate/1200)
MonthlyPayment = float(LoanAmount * MonthlyRate / (1- 1/ pow(1+MonthlyRate, NumOfYears *12)))
TotalPayment = format(MonthlyPayment * NumOfYears * 12, ".2f")
print (format(AnnualRate, ".3f"), end = "%\t\t")
print (format(MonthlyPayment, ".2f"), end = "\t\t")
print(TotalPayment, end = "\n")
AnnualRate += 1.0/8

When you work with money use the decimal module. This allows many different rounding modes. For example, round down:
import decimal
payment = decimal.Decimal('189.286')
with decimal.localcontext() as ctx:
ctx.rounding = decimal.ROUND_DOWN
print(round(payment, 2))
Prints:
189.28
Bankers' rounding would be:
decimal.ROUND_HALF_EVEN
Round to nearest with ties going to nearest even integer.
with decimal.localcontext() as ctx:
ctx.rounding = decimal.ROUND_HALF_EVEN
print(round(payment, 2))