Python: I can't figure out why this crashes.

[Arazu]

This used to work. I must have accidentally altered a character or something.

Note: The odd part is that I can drag and drop various parts of it into the interpreter and they run fine. I can get it to output it to a file just fine by dragging the function over. It crashes where commented when I attempt to run the entire thing.

#! /usr/bin/python


def get_run():
    r = raw_input('\n\nRun again? (y/n): ')
    while r != 'y' and r != 'Y' and r != 'n' and r != 'N':
        r = raw_input('Run again? (y/n): ')
    if r == 'Y':
        r = 'y'
    return r


def get_dest():
    d = ''
    while d != 's' and d != 'S' and d != 'f' and d != 'F':
        d = raw_input('Output to (F)ile or (S)creen?: ')
    if d == 'S': d = 's'
    if d == 'F': d = 'f'
    return d


def fib_calc(d):
    n = long(raw_input('\nPlease enter a number: '))
    if n >= 0:
        a, b, output = 0, 1, [0]
        while b <= n:
            output.append(b)
            a, b = b, a + b
        if d == 's':
            print '\nFibanacci numbers <=', n, '\n',
            print output,
        elif d == 'f':
            fname = 'Desktop/FibOutput' + str(n)
            print fname
            check = raw_input('one')
#crash here --->
            f = open(fname, 'w')
            check = raw_input('two')
            f.write(str(output))
            f.close
            print '\nResults written to ', fname,
    else: print '\nError: Unsupported number.',


run =  'y'
while run == 'y':
    dest = get_dest()
    fib_calc(dest)
    run = get_run() 

Thanks for any thoughts.

[elCabron]

Are you running it while inside a different directory (not containing a Desktop directory) ?

[Arazu]

I've tried it both ways. It used to work from Documents.

I'm just going to re-write it. I've already found tons of things I need to do better. I am curious why it fails though.

[namegame]

I copied and pasted your code into a file called "test.py" and ran it VIA commandline with the command "python test.py" It worked for me, both ways, with a file, and to screen. I have Python 2.4.3.

Maybe you have hidden characters in your file or something.

[Arazu]

douglas@Prometheus:~/Documents/PythonScripts$ python Fibonacci.py
Output to (F)ile or (S)creen?: f

Please enter a number: 3
Desktop/FibOutput3
one
Traceback (most recent call last):
  File "Fibonacci.py", line 46, in <module>
    fib_calc(dest)
  File "Fibonacci.py", line 36, in fib_calc
    f = open(fname, 'w')
IOError: [Errno 2] No such file or directory: 'Desktop/FibOutput3' 

I moved the .py file to my desktop and changed fname to fname = 'FibOutput' + str(n).

Now it works. I don't know why it worked last night and now it's complaining at me.

[days_of_ruin]

douglas@Prometheus:~/Documents/PythonScripts$ python Fibonacci.py
Output to (F)ile or (S)creen?: f

Please enter a number: 3
Desktop/FibOutput3
one
Traceback (most recent call last):
  File "Fibonacci.py", line 46, in <module>
    fib_calc(dest)
  File "Fibonacci.py", line 36, in fib_calc
    f = open(fname, 'w')
IOError: [Errno 2] No such file or directory: 'Desktop/FibOutput3' 

I moved the .py file to my desktop and changed fname to fname = 'FibOutput' + str(n).

Now it works. I don't know why it worked last night and now it's complaining at me.

You need to change the filepath to an absolute filepath "/home/yourusername/Desktop/FibOutput"

or move your program to your home folder and run it from there.

[delfick]

A couple of things unrelated to your problem directly (seeing as the above post seems to have the solution anyways ).

instead of using while r != 'y' and r != 'Y' and r != 'n', etc you can do

while r not in ('y', 'Y', 'n', 'N')

better yet, because you're dealing with strings here, we can do

while r not in ("yYnN"):

then we can further reduce the code by doing

while r.lower() not in ("yn"):

and then when you return r, we can do
return r.lower()
instead of checking if it's capital or not.

So the first two functions become

def get_run():
    #get initial input
    r =raw_input('\n\nRun again? (y/n): ')
    
    #While the input is incorrect
    #  keep asking for correct input
    while r.lower() not in ('yn'):
        r = raw_input('Run again? (y/n): ')
        
    return r.lower()

def get_dest():
    question = 'Output to (F)ile or (S)creen?: '
    
    d = raw_input(question)
    while d.lower() not in ('sf'):
        d = raw_input(question)
    
    return d.lower() 

Then we can see that the two functions are very similar, so we can create a decorator function that reduces code repetition a little more

def get_value(f):
    def replacementFunc():
        options = f()
        if len(options) == 2:
            question1, acceptableInput = options
            question2 = question1
        
        elif len(options) == 3:
            question1, acceptableInput, question2 = options
        
        d = raw_input(question1)
        while d.lower() not in list(acceptableInput):
            d = raw_input(question2)
        
        return d.lower()
    
    return replacementFunc

@get_value
def get_run():
    return ('\n\nRun again? (y/n): ',
        'yn',
        'Run again? (y/n): ',
    )

@get_value
def get_dest():
    return ('Output to (F)ile or (S)creen?: ',
        'sf',
    ) 

Whilst you could probably argue that reduces readability slightly, if you have a lot of these type of functions, that's quite a bit of typing you can save

Anywho, enough procrastination, I think I'll return to my uni studies now