Re: [Tutor] general basic question
On Wed, 8 Feb 2012 23:54:58 -0800 (PST) ken brockman krush1...@yahoo.com wrote: I'm back on the list again, and if not too late, here is the asked for trace. i've managed to replicate the original error msg, by removing the pickled file Genfacts.p, from the directory. Traceback (most recent call last): File /home/bob/Ninja/ArtyNOW2.py, line 120, in module Ginfo = General_info() File /home/bob/Ninja/ArtyNOW2.py, line 69, in General_info file4 = open(Genfacts.p, rb) IOError: [Errno 2] No such file or directory: 'Genfacts.p' Because you have deleted Genfacts.p you are trying to open an non-existing file. So check if the file exists before opening it. Bye, Andreas ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
Hi Ken, Welcome to Python and to programming in general. On 8 February 2012 13:40, ken brockman krush1...@yahoo.com wrote: Hello all: I have a general and very basic question if I may. I am in the process of attempting to write my first python app. I wanted to collect information and save it to lists and dictionaries. My question is, is it possible to save said lists and dictionaries in the program proper, or do i need to save the information to files on the hard drive. You would save the information in files external and seperate to the source code of your program. Note however that you can in fact directly serialize or persist (fancy object oriented terms that basically means to save to permanent storage, e.g. disk) Python objects very easily with Python standard functionality, referred to in Python terms as pickling. See the pickle module for more information: http://docs.python.org/library/pickle.html Note that it is more common for applications to use a database for data storage, such as SQLite, Postgres, MySQL, SQL Server etc etc, rather than simple pickling, but for simple cases it (or even simple text files) might suffice. It all depends on your requirements... ;) Regards Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
Hi Ken, On 8 February 2012 14:17, ken brockman krush1...@yahoo.com wrote: Thank you Walter for your help and speedy reply. You're welcome. Using pickling I have somehow managed to save two separate lists, but the dictionary is giving me much more of a struggle. Well do post back if you don't manage to solve your issues (with full error messages stack traces as relevant please.) Re dictionaries -- I actually forgot to mention, there's a specialized type of dictionary class available in Python, called a shelf, implented/available via the shelve module, which is basically a dict with pickling built in. See here: http://docs.python.org/library/shelve.html HTH, Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
On Wed, Feb 8, 2012 at 12:33 PM, ken brockman krush1...@yahoo.com wrote: Using pickling I have somehow managed to save two separate lists, but the dictionary is giving me much more of a struggle. Well do post back if you don't manage to solve your issues (with full error messages stack traces as relevant please.) Re dictionaries -- I actually forgot to mention, there's a specialized type of dictionary class available in Python, called a shelf, implented/available via the shelve module, which is basically a dict with pickling built in. See here: http://docs.python.org/library/shelve.html HTH, Walter Walter, you're the man. I've read of the shelve command. Not that i understood it, but i've read it. I'm going to hit the books and google some more before i waste anymore of your time. But if i can't sort it out, I may just take you up on your kind offer. Have a good day . Ken ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor You might want to find some tutorials that suit you. On the right column of this site there is a list of several online: www.reddit.com/r/Python/ -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
On Wed, Feb 8, 2012 at 2:57 PM, ken brockman krush1...@yahoo.com wrote: On Wed, Feb 8, 2012 at 12:33 PM, ken brockman krush1...@yahoo.com wrote: Using pickling I have somehow managed to save two separate lists, but the dictionary is giving me much more of a struggle. Got it. I manage to get it to save to disk, but only by using the shell to create an empty dictionary then pickling it and saving it to a file. Priming the pump as it were. I had thought i had read that when you pickle and save a list or dictionary to file, if it didn't already exist, it would be created. That hasn't been my experience. Had I misunderstood or Am i doing something wrong? Just for future reference. I'm as happy as the proverbial pig in excrement just to get it to function. Thanks all for your help. Ken Ken, Let me see if I understand your problem. You are pickling a dictionary and finding that it will not work unless there already is an existing dictionary for your pickled dictionary to write over. Otherwise, there is either no write at all or the write is followed by a delete. Is that a reasonable definition of your current problem? Robert Berman ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
On Wed, Feb 8, 2012 at 4:28 PM, ken brockman krush1...@yahoo.com wrote: Got it. I manage to get it to save to disk, but only by using the shell to create an empty dictionary then pickling it and saving it to a file. Priming the pump as it were. I had thought i had read that when you pickle and save a list or dictionary to file, if it didn't already exist, it would be created. That hasn't been my experience. Had I misunderstood or Am i doing something wrong? Let me see if I understand your problem. You are pickling a dictionary and finding that it will not work unless there already is an existing dictionary for your pickled dictionary to write over. Otherwise, there is either no write at all or the write is followed by a delete. Is that a reasonable definition of your current problem? Robert Berman Really close to it Robert. No delete but an error msg. Something akin to file dosen't exist, not found , or words to that effect . Ken ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Ken, The best way to get help here is to post a small example of your code that shows the problem, along with the complete traceback. Although at first they seem a little daunting, the traceback will make the problem obvious -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
On 08/02/12 21:28, ken brockman wrote: Really close to it Robert. No delete but an error msg. Something akin to file dosen't exist, not found , or words to that effect . Without sight of code it's only a guess but are you creating the file with the 'wb' mode - ie. write binary? :- myPickleFile = open(somefilename.dat, wb) If you are not using the 'b' for binary pickle and shelve tend to run into problems, this might be one of those cases. Its not glaringly obvious from the docs that you need to use binary mode and beginners often get caught out. Could that be it? -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] general basic question
ken brockman wrote: Really close to it Robert. No delete but an error msg. Something akin to file dosen't exist, not found , or words to that effect . Something akin to? How about if you copy and paste the actual error message, instead of asking us to guess? That means the full traceback, starting at the line Traceback (most recent call last) all the way to the end. It may also help if you show us the code that you are running, again instead of making us guess. But before you do, please read this document: http://sscce.org/ -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
