You have two accounts, a credit card and a checking account. You download your statements every month, and now you want to generate a report that shows you how much you made per month vs how much you spent. The catch is that you don't always make credit card payments in the same month that you purchased the items, so you want to take that into account.
Your credit card statements look like this:
| Description | Amount | Date |
|---|---|---|
| Some product | $10.00 | 2014-02-04 |
| Payment Thank You | $-100.00 | 2014-02-05 |
- All amounts are in the same column
- Payments are shown as negative amounts, with the description "Payment Thank You"
- When you purchase things with the card, they appear as positive amounts
- These are CSV files
Your checking account statements look like this:
| Description | Credit | Debit | Date |
|---|---|---|---|
| Check #34 | $15.00 | 2014-02-03 | |
| Deposit ATM | $4,000.00 | 2014-02-04 | |
| Payment CC | $100.00 | 2014-02-05 |
- All amounts are positive
- Credit and Debit are separated into separate columns
- Debit means money left your account
- Credit means you deposited money
- Deposit descriptions may vary
- Credit card payments have the description "Payment CC"
- These are CSV files
Your mission, should you choose to accept it, is to write code to determine your true month-to-month balance, using the following formula:
Deposits - (Non-credit-card Withdrawals + Credit Card Purchases)
Let's say you have the following data in a given month:
Credit Card
| Description | Amount | Date |
|---|---|---|
| Some product | $10.00 | 2014-02-04 |
| Other product | $5.00 | 2014-02-04 |
| Payment Thank You | $-100.00 | 2014-02-05 |
Checking Account
| Description | Credit | Debit | Date |
|---|---|---|---|
| Check #34 | $20.00 | 2014-02-03 | |
| Deposit ATM | $100.00 | 2014-02-04 | |
| Payment CC | $100.00 | 2014-02-05 |
Your monthly balance for the month would be $65.00 because:
Deposits - (Non-credit-card Withdrawals + Credit Card Purchases)
100.00 - (Non-credit-card Withdrawals + Credit Card Purchases)
100.00 - (20.00 + Credit Card Purchases)
100.00 - (20.00 + 15.00)
65.00
Your code should eventually be able to:
- take a directory name
- read all statements in that directory
- do the math
- return an array of months and balances
How you get there is, of course, up to you :)
Consider using the Money Gem so you don't end up with floating point math errors.
Parse all of files in the data directory. You should get the following balances:
| Year | Month | Balance |
|---|---|---|
| 2014 | January | $374.94 |
| 2014 | February | $30.79 |
| 2014 | March | $-106.04 |
| 2014 | April | $292.38 |
| 2014 | May | $-37.62 |
| 2014 | June | $-71.33 |
- Fork
- Clone
- Turn on TravisCI for the fork by visiting https://travis-ci.org/profile/, clicking the "Sync now" button and scrolling down to find the repository to build.
- Create a new branch for your work using
git checkout -b v1 - Implement specs and code
- Push using
git push -u origin v1
This warmup can be completed multiple times to increase your comfort level with the material. To work on this from scratch, you can:
- Add an upstream remote that points to the original repo
git remote add upstream git@github.com:gSchool/THIS-REPO.git - Fetch the latest from the upstream remote using
git fetch upstream - Create a new branch from the master branch of the upstream remote
git checkout -b v2 upstream/master - Implement specs and code
- Push using
git push -u origin v2
Each time you do the exercise, create a new branch. For example the 3rd time you do the exercise the branch name will be v3 instead of v2.