CS21 Lab4: while loops
This lab assignment requires you to write three programs in Python. First, run update21. This will create the cs21/labs/04 directory and copy over any starting-point files for your programs. Next, move into your cs21/labs/04 directory and begin working on the Python programs for this lab. The pwd command helps you verify that you are in the correct sub-directory.
$ update21 $ cd cs21/labs/04 $ pwd /home/your_user_name/cs21/labs/04We will only grade files submitted by handin21 in this directory, so make sure your programs are in this directory!
As you write your first programs, start using good programming practices now:
- Use a comment at the top of the file to describe the purpose of the program.
- Use variable names that describe the contents of the variables.
- Use def main() to combine the steps of your program into a function.
- Write your programs incrementally and test them as you go. This is really crucial to success: test, test again, and then test some more! Don't assume that if your program passes the sample tests we provide that it is completely correct. Come up with your own test cases and verify that the program is producing the right output on them.
Write a program that displays a download status bar to the terminal screen. Your program should ask for the size of the file (in MB), and then display the status of the download as shown below. Since we can't really download a file, we will simulate this with a while loop and the random library. Assume the file is downloaded in chunks, where the size of each chunk is chosen using randrange().
Each time another chunk of the file is downloaded, your status bar should update the display. The program should continue downloading until 100% of the file is done.
Here are some sample runs of the program.
$ python download.py size of download in MB: 400 0% 100% ( 0MB) 0% # 100% ( 8MB) 0% ### 100% ( 27MB) 0% ###### 100% ( 51MB) 0% ####### 100% ( 59MB) 0% ######### 100% ( 75MB) 0% ############# 100% (108MB) 0% ############# 100% (109MB) 0% ################ 100% (135MB) 0% ################## 100% (144MB) 0% ################### 100% (154MB) 0% ################### 100% (155MB) 0% ####################### 100% (190MB) 0% ######################### 100% (206MB) 0% ########################## 100% (213MB) 0% ############################## 100% (244MB) 0% ################################## 100% (278MB) 0% ##################################### 100% (298MB) 0% ####################################### 100% (313MB) 0% ######################################### 100% (328MB) 0% ########################################### 100% (351MB) 0% ################################################ 100% (384MB) 0% ################################################## 100% (400MB) $ python download.py size of download in MB: 130 0% 100% ( 0MB) 0% ##### 100% ( 14MB) 0% ############### 100% ( 39MB) 0% ################# 100% ( 46MB) 0% ##################### 100% ( 56MB) 0% #################################### 100% ( 95MB) 0% ################################################ 100% (126MB) 0% ################################################# 100% (129MB) 0% ################################################## 100% (130MB)
Requirements:
- make the randomly-sized chunks anywhere from 0-40 MB in size
- display the progress graphically using up to 50 pound signs
- also display the progress numerically using the number of MBs downloaded so far
- use print formatting to make everything line up as shown above
- since this is just a fake download, don't worry if the last chunk adds up to more than the total (just force it to be the remaining amount)
Write a program that shows how credit card debt payments are affected by the amount paid each month. For example, your program could show the difference between paying only the minimum amount each month versus paying an additional $100.
Assume the following about the credit card and the debt:
- the initial balance on the card is $2000
- the interest rate on the card is 20%
- the minimum payment is 3% of the current balance, or $10, whichever is larger
Your program should ask the user how much extra they want to pay each month, above the minimum amount (e.g., 10 dollars, 20, etc). It should then calculate the interest and payments each month, until the debt is paid.
Here's how the program should work:
$ python ccpayoff.py
Credit Card Balance: $2000.00
Interest Rate: 20%
Minimum Payment: 3%
------------------------------
Extra amount paid each month: 0
------------------------------
Balance InterestAmt PrinAmt Payment Paid Months
$2000.00 $ 33.33 $ 26.67 $ 60.00 $ 60.00 1
$1973.33 $ 32.89 $ 26.31 $ 59.20 $ 119.20 2
$1947.02 $ 32.45 $ 25.96 $ 58.41 $ 177.61 3
$1921.06 $ 32.02 $ 25.61 $ 57.63 $ 235.24 4
$1895.45 $ 31.59 $ 25.27 $ 56.86 $ 292.11 5
$1870.18 $ 31.17 $ 24.94 $ 56.11 $ 348.21 6
$1845.24 $ 30.75 $ 24.60 $ 55.36 $ 403.57 7
$1820.64 $ 30.34 $ 24.28 $ 54.62 $ 458.19 8
$1796.36 $ 29.94 $ 23.95 $ 53.89 $ 512.08 9
...
...
$ 70.31 $ 1.17 $ 8.83 $ 10.00 $4175.18 176
$ 61.48 $ 1.02 $ 8.98 $ 10.00 $4185.18 177
$ 52.51 $ 0.88 $ 9.12 $ 10.00 $4195.18 178
$ 43.38 $ 0.72 $ 9.28 $ 10.00 $4205.18 179
$ 34.11 $ 0.57 $ 9.43 $ 10.00 $4215.18 180
$ 24.67 $ 0.41 $ 9.59 $ 10.00 $4225.18 181
$ 15.09 $ 0.25 $ 9.75 $ 10.00 $4235.18 182
$ 5.34 $ 0.09 $ 5.34 $ 5.43 $4240.60 183
$ python ccpayoff.py
Credit Card Balance: $2000.00
Interest Rate: 20%
Minimum Payment: 3%
------------------------------
Extra amount paid each month: 100
------------------------------
Balance InterestAmt PrinAmt Payment Paid Months
$2000.00 $ 33.33 $ 126.67 $ 160.00 $ 160.00 1
$1873.33 $ 31.22 $ 124.98 $ 156.20 $ 316.20 2
$1748.36 $ 29.14 $ 123.31 $ 152.45 $ 468.65 3
$1625.04 $ 27.08 $ 121.67 $ 148.75 $ 617.40 4
$1503.38 $ 25.06 $ 120.05 $ 145.10 $ 762.50 5
$1383.33 $ 23.06 $ 118.44 $ 141.50 $ 904.00 6
$1264.89 $ 21.08 $ 116.87 $ 137.95 $1041.95 7
$1148.02 $ 19.13 $ 115.31 $ 134.44 $1176.39 8
$1032.72 $ 17.21 $ 113.77 $ 130.98 $1307.37 9
$ 918.95 $ 15.32 $ 112.25 $ 127.57 $1434.94 10
$ 806.69 $ 13.44 $ 110.76 $ 124.20 $1559.14 11
$ 695.94 $ 11.60 $ 109.28 $ 120.88 $1680.02 12
$ 586.66 $ 9.78 $ 107.82 $ 117.60 $1797.62 13
$ 478.84 $ 7.98 $ 106.38 $ 114.37 $1911.98 14
$ 372.45 $ 6.21 $ 104.97 $ 111.17 $2023.16 15
$ 267.49 $ 4.46 $ 105.54 $ 110.00 $2133.16 16
$ 161.94 $ 2.70 $ 107.30 $ 110.00 $2243.16 17
$ 54.64 $ 0.91 $ 54.64 $ 55.55 $2298.71 18
Here's the algorithm for calculating monthly interest and payments (using the first line from the last example above):
- interest amount = balance * (interest rate/12)
EX: $33.33 = $2000 * (0.2/12)
- minimum amount = minimum payment * balance
EX: $60.00 = 0.03 * $2000 [Note: if this is less than $10, set it to $10]
- payment = minimum amount + extra
EX: $160.00 = $60 + $100 [Note: if this is MORE than the balance + the interest amt, set it = balance + interest amt]
- principle amount paid = payment - interest amount
EX: $126.67 = $160.00 - $33.33
- update the balance: balance = balance - principle amount paid
Write a program to play "guess-N coin flips". Your program should ask
for the number of coinflips to guess, then repeat the following until
the user guesses the correct sequence of coinflips:
- get the user's guess (for all N flips)
- flip the coins and compare to the guess
Below are some sample runs showing how your program should work.
$ python guessNflips.py number of flips to guess: 1 guess the next 1 [ex: H]: H You guessed: H Flip Seq: T Nope...try again. ------------------------------ guess the next 1 [ex: H]: H You guessed: H Flip Seq: T Nope...try again. ------------------------------ guess the next 1 [ex: H]: H You guessed: H Flip Seq: H You did it! You correctly guessed the sequence!!
$ python guessNflips.py number of flips to guess: 4 guess the next 4 [ex: HHHT]: HHTH You guessed: HHTH Flip Seq: TTTT Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: TTTT You guessed: TTTT Flip Seq: HHHT Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: HHTH You guessed: HHTH Flip Seq: HTTT Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: THTH You guessed: THTH Flip Seq: TTTH Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: THHT You guessed: THHT Flip Seq: HHTH Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: HHHT You guessed: HHHT Flip Seq: TTHT Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: TTHT You guessed: TTHT Flip Seq: HTTH Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: TTHH You guessed: TTHH Flip Seq: HTTH Nope...try again. ------------------------------ guess the next 4 [ex: HHHT]: THTH You guessed: THTH Flip Seq: THTH You did it! You correctly guessed the sequence!!
Remember you may run handin21 as many times as you like. Each time you run it new versions of your files will be submitted. Running handin21 after you finish a program, after any major changes are made, and at the end of the day (before you log out) is a good habit to get into.