def main():
#Get amount of principal, apr, and # of years from user
princ = eval(input("Please enter the amount of principal in dollars "))
apr = eval(input("Please enter the annual interest rate percentage "))
years = eval(input("Please enter the number of years to maturity "))
#Convert apr to a decimal
decapr = apr / 100
#Use definite loop to calculate future value
for i in range(years):
princ = princ * (1 + decapr)
print('{0:5d} {0:5d}'.format(years, princ))
I'm trying to print the years and the principal value in a table, but when I print all that comes out is two columns of 10.
So you have several problems. The first problem is a display issue.
Your output statement print('{0:5d} {0:5d}'.format(years, princ)) has several issues.
printing years instead of i, so it's always the same value instead of incrementing
the 0 in the format statement{0:5d} means the 0'th element out of the following values, so you're actually printing years twice, the second one should be 1 instead of 0
you're using d to print what should be a floating point value, d is for printing integers, you should be using something along the lines of {1:.2f} which means "print this number with 2 decimal places
Once you've corrected those you'll still see incorrect answers because of a more subtle problem. You're performing division with integer values rather than floating point numbers, this means that any decimal remainders are truncated, so apr / 100 will evaluate to 0 for any reasonable apr.
You can fix this problem by correcting your input. (As a side note, running eval on user input is usually an incredibly dangerous idea, since it will execute any code that is entered.) Instead of eval, use float and int to specify what types of values the input should be converted to.
The following is corrected code which implements the above fixes.
#Get amount of principal, apr, and # of years from user
princ = float(input("Please enter the amount of principal in dollars "))
apr = float(input("Please enter the annual interest rate percentage "))
years = int(input("Please enter the number of years to maturity "))
#Convert apr to a decimal
decapr = apr / 100
#Use definite loop to calculate future value
for i in range(years):
princ = princ * (1 + decapr)
print('{0} {1:.2f}'.format(i, princ))
Related
Currently, I am supposed to create a program that "The program should have variables for the amount, number of toonies, number of loonies, number of quarters, number of dimes and number of nickels. Assume that the user will always enter an amount to the nearest nickel (no pennies). Display all of the information clearly in the output of the program." I am thinking that I could possibly use the modulus operator to calculate the remainder of coins.
Currently, I have tried to use the float function for the input of the initial value of the program and the int value for the other coins.
print ("Hello and Welcome to the Make Change Machine")
Value =float(input("Please enter the amount in dollars and cents:"))
print ("In $",Value,"there are:")
loonie = int(Value/1)
toonie = int(Value/2)
quarters = int((Value-loonie)/0.25)
dimes = int(((Value-loonie)-quarters*0.25)/0.10)
nickel = int(((Value-loonie)- quarters*0.25 - dimes*0.10)/0.05)
print ("Toonies:",toonie)
print("Loonie:",loonie)
print ("Quarters:",quarters)
print ("Dimes:",dimes)
print ("Nickels:",nickel)
I expected the output to be 3, but it ended up being 7
I am trying to create a program that asks the user their principal, interest rate, and total amount of years. I want my program to show them the amount of total return they would expect for each year. I want it to start at year 1. When I run my script, it only shows one year's worth total interest. Here is what I have so far.
#Declare the necessary variables.
princ = 0
interest = 0.0
totYears = 0
year = 1
#Get the amont of principal invested.
print("Enter the principal amount.")
princ = int(input())
#Get the interest rate being applied.
print("Enter the interest rate.")
interest = float(input())
#Get the total amount of years principal is invested.
print ("Enter the total number of years you're investing this amonut.")
totYears = int(input())
for years in range(1, totYears):
total=year*interest*princ
years += 1
print (total)
Thank you any help is appreciated.
There are problems here:
for years in range(1, totYears):
total=year*interest*princ
years += 1
print (total)
You change years within the loop. Don't. The for statement takes care of that for you. Your interference makes years change by 2 each time through the loop.
Every time through the loop, you throw away the previous year's interest and compute a new one. Your print statement is outside the loop, so you print only the final value of total.
Your loop index is years, but you've computed on the variable year, which is always 1. A programming technique I picked up many years ago is never to use a plural variable name.
Perhaps you need this:
for years in range(1, totYears):
total = years * interest * princ
print (total)
This question already has answers here:
How can I read inputs as numbers?
(10 answers)
Closed 5 months ago.
I'm a programming beginner trying to learn Python. I'm trying to complete the following exercise:
Write a program to prompt the user for hours and rate per hour to
compute gross pay.
Here's what I came up with:
hours = input("Enter number of hours worked\n")
rate = input("Enter pay rate per hour\n")
print(hours * rate)
Of course, I receive the error:
TypeError: can't multiply sequence by non-int of type 'str'
How can I tell Python that the results of the input should be regarded as integers rather than strings?
Any input from the input function is stored as string, you have to convert them both to integers before multiplying like this:
hours = input("Enter number of hours worked\n")
hours = int(hours)
rate = input("Enter pay rate per hour\n")
rate = int(rate)
print(hours * rate)
Of course you need to convert to appropriate type before multiplication, since input("") returns string of user input.
The conversion is as follows:
rate -> float
hours -> int
This is to make sure that you don't loose decimal points where user enter rate with decimals eg 2.2
So from your code you can add the following
hours = int(input("Enter number of hours worked\n"))
rate = float(input("Enter pay rate per hour\n"))
print(hours * rate) # int * float gives float
Problem solved:
hours = int(input("Enter number of hours worked\n"))
rate = int(input("Enter pay rate per hour\n"))
I figured the int function had to be placed in there somewhere.
I am a beginner at python and I'm struggling with one of my (simple) college assignments. I have been given the following instructions:
A bank is offering a savings account where a yearly fee is charged. Write
a program that lets the user enter
An initial investment.
The yearly interest rate in percent.
The yearly fee.
the program should then calculate the time it takes
for the investment to double. The interest is added on once per year.
An example run of the program:
Enter the investment: 1000
Enter the interest rate: 10
Enter the fee: 10
The investment doubles after 7 years.
I have formulated the following code but am receiving an error message with regards to t. I would really appreciate if I could get some help, thanks!:
t=0
p=float(input("Enter the investment:"))
a=float(input("Enter the interest rate:"))
m=float(input("Enter the fee:"))
i=(float(a/100))
f=p
while f<=(2*p):
f=(float(f*((1+i)**t)-m)
t=t+1
print("The investment doubles after",t,"years")
I tried to write this in a way that was very easy to follow and understand. I edited it with comments to explain what is happening line by line. I would recommend using more descriptive variables. t/p/a/m/f may make a lot of sense to you, but going back to this program 6 months from now, you may have issues trying to understand what you were trying to accomplish. NOTE You should use input instead of raw_input in my example if using Python 3+. I use 2.7 so I use raw_input.
#first we define our main function
def main():
#investment is a variable equal to user input. it is converted to a float so that the user may enter numbers with decimal places for cents
investment = float(raw_input("Starting Investment: "))
#interest is the variable for interest rate. it is entered as a percentage so 5.5 would equate to 5.5%
interest = float(raw_input("Interest Rate as %, ex: 5.5 "))
#annual_fee is a variable that will hold the value for the annual fee.
annual_fee = float(raw_input("Annual Fee: "))
#years is a variable that we will use with a while loop, adding 1 to each year (but we wait until within the loop to do this)
years = 1
#we use a while loop as opposed to a for loop because we do not know how many times we will have to iterate through this loop to achieve a result. while true is always true, so this segment is going to run without conditions
while True:
#this is a variable that holds the value of our total money per year, this is equal to the initial investment + investment * interest percentage - our annual fee per year
#I actually had to try a few different things to get this to work, a regular expression may have been more suited to achieve an interest % that would be easier to work with. do some research on regular expressions in python as you will sooner or later need it.
total_per_year = investment + (years * (investment * (interest / 100))) - (annual_fee * years)
#now we start adding 1 to our years variable, since this is a while loop, this will recalculate the value of total_per_year variable
years += 1
#the conditional statement for when our total_per_year becomes equal to double our initial investment
if total_per_year >= 2 * investment:
#print years value (at time condition is met, so it will be 5 if it takes 5 years) and the string ' Years to Double Investment'
print years,' Years to Double Investment'
#prints 'You will have $' string and then the value our variable total_per_year
print 'You will have $', total_per_year
#this will break our while loop so that it does not run endlessly
break
#here is error handling for if the fee is larger than investment + interest
if (years * annual_fee) >= (years * (investment * (interest / 100))):
print('Annual Fee Exceeds Interest - Losing Money')
break
#initial call of our main function/begins loop
main()
Having some trouble grasping why this "quick math" formula I was taught in high school does not seem to work correctly.
The premise is to take your hourly salary, double it and add three Zeros, the result will roughly equate to your yearly salary if you work full time 50 weeks out of the year.
# Preface
print '---> Want to know your yearly salary? <---'.upper()
# Question
money = raw_input("How much money do you earn per hour?")
# Math Work
mult = money * 2
result = mult + str(000)
# Answer
print "you make roughly $%r per year, Working full-time for 50 weeks out of the year" % result
Result:
my result looks something like this: "you make roughly $10100 per year, working full-time for 50 weeks out of the year"
I must be making a mistake in my expression...Simply put, I just do not know
You got all the types wrong.
raw_input acquires a string, so money is acquired as such. Thus, when you do mult=money*2 you are not doubling a number, but a string; writing money*2 thus has the effect of creating a string that is the concatenation of two copies of the string you provided. If you enter 10, mult will be '1010'.
Also, in str(000) 000 is an integer, so it's actually a plain 0; str(000) thus results in '0', which is concatenated to your doubled-string. 1010 concatenated with '0' => 10100.
What you actually want is
# Question
money = int(raw_input("How much money do you earn per hour?"))
# Math Work
mult = money * 2
result = str(mult) + "000"
By the way, adding zeroes and the like is fine for humans, but since we are dealing with a computer you can just multiply by 2000:
result = 2000*int(raw_input("How much money do you earn per hour?"))
You're trying to do math with a string. Convert it into an integer first:
money = int(raw_input("How much money do you earn per hour?"))
and multiply instead of trying to add a string to the end
result = money * 2000
Though if you really wanted to, you could convert the integer back to a string to add 3 zeros to the end:
mult = money * 2
strmult = str(mult)
result = strmult + '000'
The raw_input() function returns a string.
When you multiply money by a number, instead of multiplying the integer value, you are multiplying the string value. This results in the variable's new value being a multiple of the string, or the string repeated multiple times. I would suggest using the money=int(money) function on money to turn it into an integer, or better yet money=float(money) to get a floating-point number.
try this
money=int(input('how much you make an hour'))
final_yearly=money*2000
print(final_yearly)
You do realize the following would give you the desired answer, right?
#Math Work
mult = money * 2000
First, money is a string, when you read user input. So when the user inputs 10, you get '10'.
So when you do money*2, you don't get the expected 20. Rather, you get '10'*2, which is '10' concatenated twice, i/e/ '1010'.
Next, 000 is an int that evaluates to 0, the str of which is '0'. What you wanted to add is '000'
I would go about your task this way:
# Preface
print '---> Want to know your yearly salary? <---'.upper()
# Question
money = int(raw_input("How much money do you earn per hour?"))
# Math Work
mult = money * 2
result = str(mult) + "000"
Alternatively, you could do this as well:
# Preface
print '---> Want to know your yearly salary? <---'.upper()
# Question
money = int(raw_input("How much money do you earn per hour?"))
# Math Work
result = money*2000 # because adding three 0s is the same as multiplying by 1000
# Preface
print '---> Want to know your yearly salary? <---'.upper()
# Question
money = raw_input("How much money do you earn per hour?")
# Math Work
result = str(int(money)*2) + '000'
# Answer
print "you make roughly $%r per year, Working full-time for 50 weeks out of the year" % result