"dynamical" importing
Hello, I need to import modules from user defined paths. I.e. I want to do something like: module_dir = sys.argv[1] my_path = os.path.join(module_dir, 'bin', 'my_module') from my_path import my_object Obviously, it doesn't work this way. How would it work? Jörg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: "dynamical" importing
Thanks a lot to all. -- http://mail.python.org/mailman/listinfo/python-list
more than 100 capturing groups in a regex
Hello, Python regular expressions must not have more than 100 capturing groups. The source code responsible for this reads as follows: # XXX: get rid of this limitation! if p.pattern.groups > 100: raise AssertionError( "sorry, but this version only supports 100 named groups" ) I have been waiting a long time now for Python to get rid of this limitation. I could make a program of mine a lot faster with an easy hack if Python did not have it. My question is: Does anyone know if the problem is going to be fixed in the next few months or so? Or is there a way to circumvent it? Jörg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> Some people, when confronted with a problem, think "I know, > I'll use regular expressions." Now they have two problems. > --Jamie Zawinski Thanks for the citation. If my goal had been to redesign my program, I would not ask questions about regular expressions. I do not have the time to redesign my program. And knowing that my situation would be better, if I had written other code in the past, does not help me at all. I just want to use more than 100 capturing groups. If someone told me that it is very unlikely for Python to get rid of the said limitation, I would recode part of my program in C++ using pcre. But I would prefer to be able to do everything in Python. That is why I asked. Jörg -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> What happens if you up the limit to whatever you need? Good idea. I just tried this. Nothing evil seems to happen. This seems to be a solution. Thanks. Jörg -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
No limitation at all would be best. If a limitation is necessary, then the more capturing groups, the better. At the time being, I would be really happy about having the possibility to use 1 capturing groups. Jörg -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> but what is the reason for so much capturing groups? I > imagine that coding this and keeping code maintenable is a huge effort. User input is compiled to regular expressions. The user does not have to worry about those groups. -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> The joys of open source. Just remember you have now > made your program > non-portable. Hope this isn't an issue. Of course portability is an issue -- on the long run. But on the short run I am really glad to be able to do a 1 second demo run on my notebook instead of a 20 seconds demo run. And I am especially glad to get this 1 second demo by doing a 30-minute hack. (Hopefully ...) -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
You did not quite understand me. I will give you some details:
My program is a compiler for a certain type of linguistic grammars.
I.e. the user gives *grammar files* to my program. When the grammar
files have been compiled, they can be applied to strings (of a certain
language, e.g. English).
In the grammar files, the user does not have to deal with "capturing
groups". He even does not have to deal with regular expressions. He
just writes a grammar of a certain type. My program then compiles the
grammar into a cascade of transducers. Each of the transducers is
internally represented as a pair (REGEX, ACTION), where REGEX is a
Python regular expression and ACTION a Python function. I.e.: The
meaning of the grammar is: For each line of the input string: if REGEX
matches the line, then apply ACTION to it.
On various levels, the user may produce *disjunctions*. At the time
being, these disjunctions are internally represented by something like:
if regex1: action1()
elif regex2: action2()
elif ...
eliif regexn: actionn()
It would be nicer (and faster) to have just one regex and run that
action A such that the *capturing group* with name A ("?P...")
matched.
Now, I could of course internally create my very own transducers. But
the re module is a module that generates fsa and fsa do part of the
work that a transducer does. So why reinvent the wheel?
Jörg
--
http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> if you want to know why 100 is a reasonable and non-random choice, I > suggest checking the RE documentation for "99 groups" and the special > meaning of group 0. I have read everything I found about Python regular expressions. But I am not able to understand what you mean. What is so special about 99? -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
So what? -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
My first test program was far too naive. Evil things do happen. Simply removing the code that restricts the number of capturing groups to 100 is not a solitution. -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
... solution -- http://mail.python.org/mailman/listinfo/python-list
Re: more than 100 capturing groups in a regex
> It's a conflict between python's syntax for regex back > references and > octal number literals. Probably wasn't noticed until way > too late, and > now it will never change. So "reasonable choice" is not a really good description of the phenomenon. -- http://mail.python.org/mailman/listinfo/python-list
os.system()
Hello, code like os.system(command) only works for some values of 'command' on my system (Linux). A certain shell command (that *does* run on the command line) does not work when called with os.system(). Does anyone know a simple and stable way to have *any* string executed by the shell? Jörg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: os.system()
Well, I can give you the string, but that will not help: transduce abc info_dic comp_dic input_file output_file For copy right reasons, I am not allowed to give you the program transduce. But here are some facts about transduce: - it is written in C - it takes an alphabet file (abc) and two automata files (info_dic and comp_dic) as input and applies the automata files to the input file. -- http://mail.python.org/mailman/listinfo/python-list
Re: os.system()
> Several variables like PATH "normally" get reset even when > running a non-login subshell It seems that this has been the problem. I guess your tip saved me a lot of time. Thanks a lot. Joerg -- http://mail.python.org/mailman/listinfo/python-list
Re: os.system()
> Several variables like PATH "normally" get reset even when > running a non-login subshell It seems that this has been the problem. I guess your tip saved me a lot of time. Thanks a lot. Joerg -- http://mail.python.org/mailman/listinfo/python-list
shuffle the lines of a large file
Hello, I am looking for a method to "shuffle" the lines of a large file. I have a corpus of sorted and "uniqed" English sentences that has been produced with (1): (1) sort corpus | uniq > corpus.uniq corpus.uniq is 80G large. The fact that every sentence appears only once in corpus.uniq plays an important role for the processes I use to involve my corpus in. Yet, the alphabetical order is an unwanted side effect of (1): Very often, I do not want (or rather, I do not have the computational capacities) to apply a program to all of corpus.uniq. Yet, any series of lines of corpus.uniq is obviously a very lopsided set of English sentences. So, it would be very useful to do one of the following things: - produce corpus.uniq in a such a way that it is not sorted in any way - shuffle corpus.uniq > corpus.uniq.shuffled Unfortunately, none of the machines that I may use has 80G RAM. So, using a dictionary will not help. Any ideas? Joerg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: shuffle the lines of a large file
Thanks to all. This thread shows again that Python's best feature is comp.lang.python. Jörg -- http://mail.python.org/mailman/listinfo/python-list
compile shebang into pyc file
Hello, is there a way to compile a python file foo.py to foo.pyc (or foo.pyo) such that foo.pyc can be run with 'foo.pyc' (as opposed to 'python foo.pyc') on the command line? Jörg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: compile shebang into pyc file
> #!/usr/bin/env python > import app Yes, of course this is a possibility. But it implies having (or giving away) two files. I think having one file is always better than having two files. Because if you have two files, you need a third one: a README that tells you what to do with the two files and that one of the files must either be in $PYTHONPATH, or in the same directory as the other one and '.' must be in your $PYTHONPATH , and so on. Actually, some people will also need a fourth file: One that contains an explanation of terms like "$PYTHONPATH" and the like. Jörg -- http://mail.python.org/mailman/listinfo/python-list
Re: compile shebang into pyc file
> so you're saying that the set of people that can deal with > no more than one > file at a time but knows how to install and configure Python > (which in itself > comes with a few thousand files) is larger than zero? Take me as an example: Very often, I needed software that could solve a specific problem. I used to find, say, 10 different packages. Usually none of the programs REALLY did the job as I wanted it to be done. Yet, in order to find this out (or in order to find the package that suited my needs best), I had to try out all of these packages. This used to take an unnecessary amount of time. I would have found (say) one java program, one c++ program, one Python program, one perl program, ... I know that java, c++, Python and Perl are all installed on our system. And if they weren't, I would know how to install them myself: By using yast or by saying 'apt-get install '. Yet: I don't want to have to know how to install all these packages in all these different languages. I think a program should work out of the box. And the should be no fumbling it out of the box. Jörg -- http://mail.python.org/mailman/listinfo/python-list
open file in dir independently of operating system
Hello, I want to open the file 'configuration.smo' that is in directory dir. Yet, I don't know on which os my program is being run. On Unix I would say: f = open(dir + '/configuration.smo', 'r') What is the os-independent version of this line? (I have read the manual of the module os, but I didn't see how to do it.) Jörg Schuster -- http://mail.python.org/mailman/listinfo/python-list
Re: open file in dir independently of operating system
Thanks, Andrew and Gerald. Jörg -- http://mail.python.org/mailman/listinfo/python-list
