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  • Python: needs more than 1 value to unpack

    - by Rosarch
    What am I doing wrong to get this error? replacements = {} replacements["**"] = ("<strong>", "</strong>") replacements["__"] = ("<em>", "</em>") replacements["--"] = ("<blink>", "</blink>") replacements["=="] = ("<marquee>", "</marquee>") replacements["@@"] = ("<code>", "</code>") for delimiter, (open_tag, close_tag) in replacements: # error here message = self.replaceFormatting(delimiter, message, open_tag, close_tag); The error: Traceback (most recent call last): File "", line 1, in for shit, (a, b) in replacements: ValueError: need more than 1 value to unpack All the values tuples have two values. Right?

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  • Best practice for Python Assert

    - by meade
    Is there a performance or code maintenance issue with using assert as part of the standard code instead of using it just for debugging purposes? Is assert x >= 0, 'x is less then zero' and better or worse then if x < 0: raise Exception, 'x is less then zero' Also, is there anyway to set a business rule like if x < 0 raise error that is always checked with out the try, except, finally so, if at anytime throughout the code x is < 0 an error is raised, like if you set assert x < 0 at the start of a function, anywhere within the function where x becomes less then 0 an exception is raised?

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  • Python: For loop problem

    - by Yasmin
    I have a simple for loop problem, when i run the code below it prints out series of 'blue green' sequences then a series of 'green' sequences. I want the output to be; if row[4] is equal to 1 to print blue else print green. for row in rows: for i in `row[4]`: if i ==`1`: print 'blue ' else: print 'green ' Any help would be grateful thanks Yas

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  • Python __import__ parameter confusion

    - by CMC
    I'm trying to import a module, while passing some global variables, but it does not seem to work: File test_1: test_2 = __import__("test_2", {"testvar": 1}) File test_2: print testvar This seems like it should work, and print a 1, but I get the following error when I run test_1: Traceback (most recent call last): File ".../test_1.py", line 1, in <module> print testvar NameError: name 'testvar' is not defined What am I doing wrong?

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  • Concise way to getattr() and use it if not None in Python

    - by MTsoul
    I am finding myself doing the following a bit too often: attr = getattr(obj, 'attr', None) if attr is not None: attr() # Do something, either attr(), or func(attr), or whatever else: # Do something else Is there a more pythonic way of writing that? Is this better? (At least not in performance, IMO.) try: obj.attr() # or whatever except AttributeError: # Do something else

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  • Access static class variable of parent class in Python

    - by fuenfundachtzig
    I have someting like this class A: __a = 0 def __init__(self): A.__a = A.__a + 1 def a(self): return A.__a class B(A): def __init__(self): # how can I access / modify A.__a here? A.__a = A.__a + 1 # does not work def a(self): return A.__a Can I access the __astatic variable in B? It's possible writing a instead of __a, is this the only way? (I guess the answer might be rather short: yes :)

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  • Python: how to execute generated code ?

    - by Natim
    Hello guys I have this code, and I would like to use the app parameter to generate the code instead of duplicating it. if app == 'map': try: from modulo.map.views import map return map(request, *args, **kwargs) except ImportError: pass elif app == 'schedule': try: from modulo.schedule.views import schedule_day return schedule_day(request, *args, **kwargs) except ImportError: pass elif app == 'sponsors': try: from modulo.sponsors.views import sponsors return sponsors(request, *args, **kwargs) except ImportError: pass elif app == 'streaming': try: from modulo.streaming.views import streaming return streaming(request, *args, **kwargs) except ImportError: pass Do you have any idea ? Thanks

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  • Python nested dict comprehension with sets

    - by Jasie
    Can someone explain how to do nested dict comprehensions? >> l = [set([1, 2, 3]), set([4, 5, 6])] >> j = dict((a, i) for a in s for i, s in enumerate(l)) >> NameError: name 's' is not defined I would have liked: >> j >> {1:0, 2:0, 3:0, 4: 1, 5: 1, 6: 1} I just asked a previous question about a simpler dict comprehension where the parentheses in the generator function were reduced. How come the s in the leftmost comprehension is not recognized?

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  • Python: how to inherite and override

    - by Guy
    Consider this situation: I get an object of type A which has the function f. I.e: class A: def f(): print 'in f' def h(): print 'in h' and I get an instance of this class but I want to override the f function but save the rest of the functionality of A. So what I was thinking was something of the sort: class B(A): .... def f(): print 'in B->f' and the usage would be: def main(a): b = B(a) b.f() #prints "in B->f" b.h() #print "in h" How do you do such a thing?

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  • python iterators and thread-safety

    - by Igor
    I have a class which is being operated on by two functions. One function creates a list of widgets and writes it into the class: def updateWidgets(self): widgets = self.generateWidgetList() self.widgets = widgets the other function deals with the widgets in some way: def workOnWidgets(self): for widget in self.widgets: self.workOnWidget(widget) each of these functions runs in it's own thread. the question is, what happens if the updateWidgets() thread executes while the workOnWidgets() thread is running? I am assuming that the iterator created as part of the for...in loop will keep some kind of reference to the old self.widgets object? So I will finish iterating over the old list... but I'd love to know for sure.

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  • Recognizing file - Python

    - by Francisco Aleixo
    Ok, so the title may trick you a bit, and I'm sorry for that but didn't find a better title. This question might be a bit hard to understand so I'll try my best. I have no idea how this works or if it is even possible but what I want to do is for example create a file type (lets imagine .test (in which a random file name would be random.test)). Now before I continue, its obviously easy to do this using for example: filename = "random.test" file = open(filename, 'w') file.write("some text here") But now what I would like to know is if it is possible to write the file .test so if I set it to open with a wxPython program, it recognizes it and for example opens up a Message Dialog automatically. I'm sorry if I'm being vague and in case you don't understand, let me know so I can try my best to explain you.

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  • Python: Converting a tuple to a string with 'err'

    - by skylarking
    Given this : import os import subprocess def check_server(): cl = subprocess.Popen(["nmap","10.7.1.71"], stdout=subprocess.PIPE) result = cl.communicate() print result check_server() check_server() returns this tuple: ('\nStarting Nmap 4.53 ( http://insecure.org ) at 2010-04-07 07:26 EDT\nInteresting ports on 10.7.1.71:\nNot shown: 1711 closed ports\nPORT STATE SERVICE\n21/tcp open ftp\n22/tcp open ssh\n80/tcp open http\n\nNmap done: 1 IP address (1 host up) scanned in 0.293 seconds\n', None) Changing the second line in the method to result, err = cl.communicate() results in check_server() returning : Starting Nmap 4.53 ( http://insecure.org ) at 2010-04-07 07:27 EDT Interesting ports on 10.7.1.71: Not shown: 1711 closed ports PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 80/tcp open http Nmap done: 1 IP address (1 host up) scanned in 0.319 seconds Looks to be the case that the tuple is converted to a string, and the \n's are being stripped.... but how? What is 'err' and what exactly is it doing?

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  • finding max in python as per some custom criterion

    - by MK
    Hi, I can do max(s) to find the max of a sequence. But suppose I want to compute max according to my own function , something like so - currmax = 0 def mymax(s) : for i in s : #assume arity() attribute is present currmax = i.arity() if i.arity() > currmax else currmax Is there a clean pythonic way of doing this? Thanks!

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  • A problem with assertRaises function in Python

    - by anton.k.
    Hello,guys! I am trying to run the following test self.assertRaises(Exception,lambda: unit_test.testBasic()) where test.testBasic() is class IsPrimeTest(unittest.TestCase): def assertRaises(self,exception,callable,*args,**kwargs): print('dfdf') temp = callable super().assertRaises(exception,temp,*args,**kwargs) def testBasic_helper(self): self.failIf(is_prime(2)) self.assertTrue(is_prime(1)) where prime is a function,and but in self.assertRaises(Exception,lambda: unit_test.testBasic()) the lambda function doesnt throws an exception after the test def testBasic_helper(self): self.failIf(is_prime(2)) self.assertTrue(is_prime(1)) fails Can somebody offers a solution to the problem?

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  • Invalid syntax in this simple Python application.

    - by Sergio Boombastic
    Getting an invalid syntax when creating the template_value variable: class MainPage(webapp.RequestHandler): def get(self): blogPosts_query = BlogPost.all().order('-postDate') blogPosts = blogPosts_query.fetch(10) if users.get_current_user(): url = users.create_logout_url(self.request.uri) url_linktext = 'Logout' else: url = url = users.create_login_url(self.request.uri) url_linktext = 'Login' template_value = ( 'blogPosts': blogPosts, 'url': url, 'url_linktext': url_linktext, ) path = os.path.join(os.path.dirname(__file__), 'index.html') self.response.out.write(template.render(path, template_values)) The error fires specifically on the 'blogPosts': blogPosts line. What am I doing wrong? Thanks!

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  • Python - Subprocess Popen and Thread error

    - by n0idea
    In both functions record and ftp, i have subprocess.Popen if __name__ == '__main__': try: t1 = threading.Thread(target = record) t1.daemon = True t1.start() t2 = threading.Thread(target = ftp) t2.daemon = True t2.start() except (KeyboardInterrupt, SystemExit): sys.exit() The error I'm receiving is: Exception in thread Thread-1 (most likely raised during interpreter shutdown): Traceback (most recent call last): File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner File "/usr/lib/python2.7/threading.py", line 504, in run File "./in.py", line 20, in recordaudio File "/usr/lib/python2.7/subprocess.py", line 493, in call File "/usr/lib/python2.7/subprocess.py", line 679, in __init__ File "/usr/lib/python2.7/subprocess.py", line 1237, in _execute_child <type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'close' What might the issue be ?

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  • Python - Things one MUST avoid

    - by Anurag Uniyal
    Today I was bitten again by "Mutable default arguments" after many years. I usually don't use mutable default arguments unless needed but I think with time I forgot about that, and today in the application I added tocElements=[] in a pdf generation function's argument list and now 'Table of Content' gets longer and longer after each invocation of "generate pdf" :) My question is what other things should I add to my list of things to MUST avoid? 1 Mutable default arguments 2 import modules always same way e.g. 'from y import x' and 'import x' are totally different things actually they are treated as different modules see http://stackoverflow.com/questions/1459236/module-reimported-if-imported-from-different-path 3 Do not use range in place of lists because range() will become an iterator anyway, so things like this will fail, so wrap it by list myIndexList = [0,1,3] isListSorted = myIndexList == range(3) # will fail in 3.0 isListSorted = myIndexList == list(range(3)) # will not same thing can be mistakenly done with xrange e.g myIndexList == xrange(3). 4 Catching multiple exceptions try: raise KeyError("hmm bug") except KeyError,TypeError: print TypeError It prints "hmm bug", though it is not a bug, it looks like we are catching exceptions of type KeyError,TypeError but instead we are catching KeyError only as variable TypeError, instead use try: raise KeyError("hmm bug") except (KeyError,TypeError): print TypeError

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  • Python Script to check website for a tag

    - by LinuxGnut
    Hello all. I'm trying to figure out how to go about writing a website monitoring script (cron job in the end) to open up a given URL, check to see if a tag exists, and if the tag does not exist, or doesn't contain the expected data, then to write some to a log file, or to send an e-mail. The tag would be something like or something relatively similar. Anyone have any ideas?

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  • Split a string in python taking care of quotes

    - by santu
    I want to extract key value pairs of some form elements in a html page for example name="frmLogin" method="POST" onSubmit="javascript:return validateAndSubmit();" action="TG_cim_logon.asp?SID=^YcMunDFDQUoWV32WPUMqPxeSxD4L_slp_rhc_rNvW7Fagp7FgH3l0uJR/3_slp_rhc_dYyJ_slp_rhc_vsPW0kJl&RegType=Lite_Home" is there any method using which I can safely get the key and value pairs. I tried using splitting by spaces and then using '=' characters but string inside quotes can also have '='. is there any different kind of split method which can also take care of quotes?

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  • Spotting similarities and patterns within a string - Python

    - by RadiantHex
    Hi folks, this is the use case I'm trying to figure this out for. I have a list of spam subscriptions to a service and they are killing conversion rate and other usability studies. The emails inserted look like the following: [email protected] [email protected] [email protected] roger[...]_surname[...]@hotmail.com What would be your suggestions on spotting these entries by using an automated script? It feels a little more complicated than it actually looks. Help would be very much appreciated!

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  • Working with multiple input and output files in Python

    - by Morlock
    I need to open multiple files (2 input and 2 output files), do complex manipulations on the lines from input files and then append results at the end of 2 output files. I am currently using the following approach: in_1 = open(input_1) in_2 = open(input_2) out_1 = open(output_1, "w") out_2 = open(output_2, "w") # Read one line from each 'in_' file # Do many operations on the DNA sequences included in the input files # Append one line to each 'out_' file in_1.close() in_2.close() out_1.close() out_2.close() The files are huge (each potentially approaching 1Go, that is why I am reading through these input files one at a time. I am guessing that this is not a very Pythonic way to do things. :) Would using the following form good? with open("file1") as f1: with open("file2") as f2: # etc. If yes, could I do it while avoiding the highly indented code that would result? Thanks for the insights!

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  • Python try/except: Showing the cause of the error after displaying my variables

    - by NealWalters
    I'm not even sure what the right words are to search for. I want to display parts of the error object in an except block (similar to the err object in VBScript, which has Err.Number and Err.Description). For example, I want to show the values of my variables, then show the exact error. Clearly, I am causing a divided-by-zero error below, but how can I print that fact? try: x = 0 y = 1 z = y / x z = z + 1 print "z=%d" % (z) except: print "Values at Exception: x=%d y=%d " % (x,y) print "The error was on line ..." print "The reason for the error was ..."

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  • Google App Engine python - Self is not defined

    - by sdasdas
    I have a request that maps to this class ChatMsg It takes in 3 get variables, username, roomname, and msg. But it fails on this last line here. class ChatMsg(webapp.RequestHandler): # this is line 239 def get(self): username = urllib.unquote(self.request.get('username')) roomname = urllib.unquote(self.request.get('roomname')) # this is line 242 When it tries to assign roomname, it tells me: <type 'exceptions.NameError'>: name 'self' is not defined Traceback (most recent call last): File "/base/data/home/apps/chatboxes/1.341998073649951735/chatroom.py", line 239, in <module> class ChatMsg(webapp.RequestHandler): File "/base/data/home/apps/chatboxes/1.341998073649951735/chatroom.py", line 242, in ChatMsg roomname = urllib.unquote(self.request.get('roomname')) what the hell is going on to make self not defined

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  • What are the steps taken with pip install in python

    - by Lawrence Chernin
    I am trying to install a package via pip, but there were missing files from the zip file. So I copy the files and then compile with gcc. But now I cannot continue with the installation by calling pip install because it sees a pre-existing directory and will not proceed. This is with pip version 1.5.6, but I thought that with earlier versions of pip that it was less fussy about this. What are the remaining steps to complete the package installation?

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