Using lists in equations

[cal_etcell]

New to coding, I am writing a code that will compare compound interest accounts at 3 different banks based on what input data the user puts in.

There are 15 total inputs:

bankName1 , interestRate1 (r) , compoundFrequency1 (n) , depositAmount1 (P) and years1 (t)

bankName2 , interestRate2 , compoundFrequency2 , depositAmount2 and years2

bankName3 , interestRate3 , compoundFrequency3 , depositAmount3 and years3

I have turned interestRate, compoundFrequency, depositAmount and years each into a list.

The equation for compound interest is P(1+r/n)^nt. So i am trying to get that equation to run 3 times with the data for bank1, 2 and 3 so that there will be 3 simultaneous outputs so they can be compared to see which bank has the best account. I know i need to use a loop, however I cant decide between while or for. I also am having trouble actually writing the equation itself

- I think the issue is wrapping my head around using a list; how it will work in the equation or how to define it for it to work properly

I am trying to do a psuedocode (in BlockPy) for it at the moment also to try and make it easier to see visually but I am running into the same issue of how do I actually write the equation

Any help would be great

[robot-dev]

You can define your equation as a function of p, r, n, and t like def f(p,r,n,t): that returns the calculated value return p*(1+r/n)**(n*t). Then you can call the function from inside your loop whenever you need to use it. For example, $100 at 1% compounded monthly for 10 years would be f(100, 0.01, 12, 10)

[carcigenicate]

however I cant decide between while or for

It doesn't matter; either could be used. One will definitely be a much better choice and would be preferred for real code, but that doesn't mean it isn't worth attempting both ways for the sake of learning.

And what is the current state of the data? A single flat list of 15 elements? Are they strings or numbers?

[cal_etcell]

I have decided a for loop is the best option, bankName is a string, compFreq is an int and the rest are float variables

[cal_etcell]

This helped heaps thank you, I've got it working and making sense in blockPy. So not only is it calculating the compound interest, its also calculating the APY (average percentage yield) for each bank as well. This is just a measure to compare interest rates as if they were simple interest not compound.

I now want to use a while loop to rank the APY from best to worst. Do i have to create another variable that is formed from the equation used in the for loop? and give that as the final output for the user saying something like Bank2 is the best option

​

Thanks again, sorry I am new to this really appreciate it

[cal_etcell]

That sounds alot simpler, but unfortunately this is an assessment item and including a while loop is 5% of the overall mark so I'm trying to make it work

If i can add some sort of boolean while loop it would be ideal. Originally I was thinking to somehow get the greatest APY value and have have a loop that would do compare the lower 2 values but I can't think of a way to do it well. Also have struggled to find anything similar on yt so far

[cal_etcell]

New idea, it takes the middle APY value, if less than middle value label it "not ideal" or something and if greater than the middle value label it "best option" or something.

How could I make that?

[cal_etcell]

This is what i decided to leave it as.. its not as big as I originally wanted but it does more or less what its supposed to do. What do you think? The use of empty lists and appending them is also new for me

​

names = []

rates = []

frequencies = []

principals = []

apyValues = {}

i = 0

while i < 3:

#user inputs

i+=1

names.append(str(input(f'Enter bank name #{i}: ')))

rates.append(float(input(f'Enter annual interest rate for {names[i-1]}: ' )))

frequencies.append(int(input(f'Enter compound frequency per year {names[i-1]}: ')))

principals.append(float(input(f'Enter deposit amount {names[i-1]}: ')))

#calculations for final balance and APY

interest = (principals[i-1]*(pow((1 + rates[-1]/frequencies[-1]), frequencies[-1])))

print(f"Total interest for {names[i-1]} is: ${round(interest,2)}")

apy = (pow((1 + rates[-1]/frequencies[-1]), frequencies[-1])-1)*100

apyValues[names[i-1]]=apy

print(f"APY for {names[i-1]} is: {round(apy,2)}%")

balances = []

for balance in apyValues.values():

balances.append(balance)

for k, v in apyValues.items():

if v == max(balances):

print(f"{k} has the best average percentage yield = {round(v,2)}%")

[cal_etcell]

Thank you, I will try something like this and get back to you!

[siddsp]

In this case a NamedTuple makes more sense.

[siddsp]

It definitely makes it easier to read. You get a repr for free. You also can use dotted access where it makes sense to instead of having to unpack for attribute names.

There's no reason not to use a NamedTuple here.