[Tutor] Still not understanding passing filenames in Python

[DL Neil]

On 7/06/20 1:47 PM, boB Stepp wrote:
> Now in "3.4 Modules" at
> https://dabeaz-course.github.io/practical-python/Notes/03_Program_organization/04_Modules.html 
> 
> 
> Earlier in the course I wrote a program, report.py, that runs as so:
> 
> bob at Dream-Machine1:~/practical-python/Work$ python3 report.py
> 
> Enter path to portfolio file:  Data/portfolio.csv
> Enter path to stock prices file:  Data/prices.csv
> 
>        Name     Shares      Price     Change ---------- ---------- 
> ---------- ----------         AA        100      $9.22     -22.98
>         IBM         50    $106.28      15.18
>         CAT        150     $35.46     -47.98
>        MSFT        200     $20.89     -30.34
>          GE         95     $13.48     -26.89
>        MSFT         50     $20.89     -44.21
>         IBM        100    $106.28      35.84
> 
> Current portfolio value = $28,686.10
> Current portfolio gain/loss = $-15,985.05
> 
> In "Exercise 3.12: Using your library module" Beazley has us importing the
> recently discussed fileparse module containing the parse_csv() function to
> replace the code previously written in the read_portfolio() function in
> report.py.  So I added "import fileparse" and modified the read_portfolio()
> function to:
> 
> def read_portfolio(filename: str) -> List[Dict[str, Union[str, int, 
> float]]]:
>      """Read a file and return a portfolio list of records."""
>      portfolio = fileparse.parse_csv(
>          filename, select=["name", "shares", "price"], types=[str, int, 
> float]
>      )
>      return portfolio
> 
> report.py and fileparse.py are both in the same Work directory.  Data is a
> subdirectory of Work.
> 
> But when I try to run this program with the same file location entries
> I get:
> 
> bob at Dream-Machine1:~/practical-python/Work$ python3 report.py
> 
> Enter path to portfolio file:  Data/porfolio.csv
> Enter path to stock prices file:  Data/prices.csv
> Traceback (most recent call last):
>    File "report.py", line 113, in <module>
>      main()
>    File "report.py", line 104, in main
>      portfolio = read_portfolio(portfolio_path)
>    File "report.py", line 18, in read_portfolio
>      filename, select=["name", "shares", "price"], types=[str, int, float]
>    File "/home/bob/practical-python/Work/fileparse.py", line 25, in 
> parse_csv
>      with open(filename) as fileobj:
> FileNotFoundError: [Errno 2] No such file or directory: 'Data/porfolio.csv'
> 
> If I use absolute file paths, "/home/bob/practical-python..." it works.
> 
> If I use "./Data/portfolio.csv" and "./Data/prices.csv" it works.  I
> currently do not understand the differences.  Obviously I do understand one
> or more things.  A helpful explanation please?  Thanks!


Please don't shoot the piano player (or the Latin teacher)...
is the fileNM correct?

 > bob at Dream-Machine1:~/practical-python/Work$ python3 report.py
 >
 > Enter path to portfolio file:  Data/portfolio.csv

...

 > bob at Dream-Machine1:~/practical-python/Work$ python3 report.py
 >
 > Enter path to portfolio file:  Data/porfolio.csv
-- 
Regards =dn