## shims506 3 years ago I'm having issues with my code for PS2 question 2 it saying that there's an error on my else statement.

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1. shims506

balance=4213 annualInterestRate=.2 factor=0 #How much paid total x=0 #Lowest payment variable y=0 #Range for one year of paying minimum 12 months in a year while balance >= 0: factor+=1 for n in range(1,13): x=str(factor)*(10*str(n)) balance=(balance-(10*str(factor)))*(1+(annualInterestRate/12) else: y=str(factor)*10 #Print Lowest Payment print('Lowest Payment: '+str(round(y,-1)))

2. dpflan

You're getting an "invalid syntax" error?

3. shims506

yes would like to know whats the reason before i procede on fixing the rest of the code

4. dpflan

Looks like you're missing a parenthesis on this line: balance=(balance-(10*str(factor)))*(1+(annualInterestRate/12)

5. dpflan

That looks to be the first problem, it's expecting a ")" to close (1+(annualInterestRate/12)

6. dpflan

On this line: " x=str(factor)*(10*str(n)) " You are trying to obtain a number, correct? the "str(x)" method converts the argument into a string.

7. dpflan

Yeah, close the parenthesis, then run the code. You should encounter another error...

8. shims506

Always the small things that gets me, thanks. Also for that section of code I am aiming at getting a number value is str() not the function? Another issue i seem to see is that shouldn't i have a void loop on the calculation of balance part because if the first time the payment isn't right and i go to check the next factor of 10 the balance will be altered do to previous run.

9. shims506

Yea got the TypeError: can't multiply sequence by non-int of type 'str' Will change that part and others like that asap.

10. dpflan

Yeah, you're working with numbers. Checkout here: http://docs.python.org/library/string.html

11. dpflan

There you can see methods/functions for string in python. str(x) converts the argument x to a string

12. dpflan

How's it going?

13. shims506

For str() i would need to convert to int because the error it shows now is TypeError: can't multiply sequence by non-int of type 'str' since working in which month and factors of ten i can change that into int() right?

14. dpflan

yeah, basically you can't multiply strings together...

15. dpflan

factor is already a number luckily

16. msmithhnova

You shouldn't need to have anything as a string to begin with. I think you are making it more complicated than it is. just leave everything as numbers. you don't even have to convert to str to print it.

17. shims506

I deleted all str() and still have an error at where i have my "else:" statement error is invalid syntax

18. dpflan

hm, did you put in that parenthesis at the end?

19. msmithhnova

You are trying to do a while ... else .... there is no such thing, just while or if..else

20. dpflan

Can you direct to me the assignment via link?

21. dpflan

But, @msmithhnova is right, your current solution may be more complicated than necessary and hence combining programing designs. if : .. else: clauses exists in python. a while: ... else: block does not exist.

22. shims506

you have to be logged in to view assignment i can send the summary of it though I change my "while" to "if" and still has same error at same location im double checking all my parenthesis

23. dpflan

24. shims506

balance=4213 annualInterestRate=.2 factor=0 #How much paid total x=0 #Lowest payment variable y=0 if balance > 0: factor+=1 #Range for one year of paying minimum 12 months in a year for n in range(1,13): x=factor*(10*n) balance=(balance-(10*factor)*(1+(annualInterestRate/12)) else: y=factor*10 #Print Lowest Payment print('Lowest Payment: '+str(round(y,-1)))

25. dpflan

cool

26. dpflan

Yep, missing a parenthesis: balance=(balance-(10*factor)*(1+(annualInterestRate/12)) <---- ) need

27. msmithhnova

Here's some pseudocode that might help set payment guess loop check guess if guess not right increase guess end loop

28. shims506

Yupp that did the trick thank you dpflan :) now time to fix the algebra part msmithhnova will that pseudo code fix the issue with balance being overwritten to a new value when increasing the guess.

29. msmithhnova

No, you will want to create a new variable equal to balance to either work with or keep track of original amoiunt.

30. msmithhnova

Another note is from the pseudocode you are looking at one while loop with everything in it. The only thing that would end up outside the loop is the print statement with your final answer.

31. msmithhnova

An issue with your code above also is that your guess (x) should be changed outside the for as the for loop is the 'check' part of the pseudocode

32. dpflan

Try to state the goal of the problem, from there, write out your solution in pseudocode, and create the mathematical relationship among variables

33. msmithhnova

BTW, dpflan, the basics of the problem is make guesses in increments of 10 that it will take to pay off balance in 1 year including interest. Once a guess makes the balance less than 0 you're done.

34. shims506

Never thought about doing a pseudo code seems like an easier cleaner route ill try that and let you know what other issues i run into. Thanks for the all the help so far.

35. dpflan

The goal is to find the factor such that the balance becomes 0 within 12 iterations

36. dpflan

You need to start each examination with balance at the starting balance.

37. dpflan

A simple debugging technique is add print statements in your code, for instance it might help to print the values you are working with, like the balance and the factor

38. shims506

that makes life so much easier thank you i seem to getting some numbers displayed printed out hopefully they are the right numbers.

39. msmithhnova

If not lets us know. Pseudocode is a wonderful thing it allows you to think about the logic and coding seperately instead of doing both at the same time. Once you think you have your logic (pseudocode) figured out then it is just a matter of turning that into actual code. When you do, you sometimes realize your logic (pseudocode) was a little off of your translation to code was and one or both have to be modified. This is where the print statements help immensely to show you where the flaw is.

40. dpflan

Yeah, feel free to share your solution when reach one. We can check out your code like we've just done and give you some help. What course is this from? An MIT OCW course, the MOOC course,...?

41. msmithhnova

Edx MIT 600 course

42. shims506

so far this is what i have in my code, added a few things to make up for the override my answer is 140 but i should be getting 310 with the current balance and interest rate i put in i will need to look more into pseudo code is there any site that teaches the concept well?

43. shims506

one thing that helped answer is i deleted "-x" in my while statement but im still \$30 off

44. shims506

balance=3329 annualInterestRate=.2 factor=0 #How much paid total x=0 #Lowest payment variable y=0 balance1=balance while balance1 >= 0: factor+=1 x=0 balance1=balance #Range for one year of paying minimum 12 months in a year for n in range(1,13): print('What Factor im on:'+str(factor)) print('Which month im on:'+str(n)) x=factor*10*n print(str(x)) balance1=(balance1-(10*factor)*(1+(annualInterestRate/12))) print('Balance so far:'+str(balance1)) amiclose=balance1-x #print(str(amiclose)) y=factor*10 #Print Lowest Payment print('Lowest Payment:'+str(y)) #actual Lowest payment should be 310

45. msmithhnova

Just headed home, will take a look when I get there if someone else hasn't by then.

46. TuringTest

you have a lot of extra variables...

47. shims506

in my new code i use those variables to check where im at and print out values if you d like i can update the code i noted what each variable does

48. TuringTest

x=factor*10*n this line is strange, why should the minimum payment be proportional to which number month of the year you are in?

49. shims506

that line states how much have i paid off the debt in which factor and this given month so i could check my math

50. shims506

aleluja i was missing a ')' and since it was following mathematical rules PEMDAS it didnt work out at first now everything seems good :) thanks all for the help

51. TuringTest

ok, still, n is the number month you are in this code is saying that you pay factor*10*2 in february, and factor810*3 in march i.e. you pay more in march then february, how does that make sense?

52. shims506

the thing is how much total have i paid up to that month you know

53. TuringTest

it makes sense that the total you have paid my march is more than in february, but you code says that you pay more for *that* particular month than the one before

54. TuringTest

I mean, if you get the right answer then okay, but I don't see how...

55. shims506

hmmm im not understanding your question their but i did submit my code and it was right thanks guys :)

56. TuringTest

okey dokey then :)

57. msmithhnova

Glad you got it to work.

58. Ecrest

What is wrong with this code: balance = 4213 annualInterestRate = 0.2 monthlyPaymentRate = 0.4 month = 1 balance = (balance - (balance*monthlyPaymentRate))*(1+(annualInterestRate/12)) while month < 13: print "Month: " + str(month) print "Minimum monthly payment: " + str(round(minimum_payment_rate, 2)) print "Remaining balance: " + str(round(balance, 2)) month += 1

59. Chris2332

where do you calculate your balance in the loop? It will remain the same. You just incrementing the month and you don't touch the min payment or the balance!