🌐 Mailman 3 June 2004 - Tutor - python.org

Output to a printer
by Bob Fleming Dec. 29, 2004

Dec. 29, 2004

I am learning Python on a Windows system (Win95). All of the tutorials, documentation, and a book that I am studying all assume printing to the console (stdout). I live in the real world and will need to print out to my laser printer or other device. How do I modify the print or write statements, or redirect stdout, to print to a printer? Thank you, Bob Fleming robertf(a)eskimo.com

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Record Locking & Access - newbye
by Miguel Lopes July 4, 2004

July 4, 2004

Hi, Here's my problem. Using python dbapi I get groups of records back from a database into a list for example to feed a "List Form" which is just a grid on a form (the db is about 9000 thousand records - so I suppose there's not a big problem to fetch all records in a go!). Now when a user selects a record from a grid on screen I can send him to another form "Record Form" where he can edit the record. This way I can have only one query to the database and have the users working locally on there record sets. But when a user edits an existing record I puzzled to think that another user might be changing that record at the same time (because they are not locking any records and are using lists with the record contents locally)! This could cause for example that user A changes record 1 from "bar" to "foo" and updates the db, just after user A user B updates the db with a change in the same record from "bar" to "foobar" (never seeing user As changes)!!! I guess this is a very common problem with a standard solution. How can I avoid this? Best regards, Mekl

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regular expressions
by Larry Blair July 4, 2004

July 4, 2004

I am trying to use regular expressions to delete a wildcard set of tables. My pattern is 'TEMP*' The code below is how I am implementing the delete. My problem is that it also deletes a file 'SYSTEM' also. I can see where the TEM parts match. First is why does it ignore the P from the patterns? Second I understand that search scans through the string looking for a match. What I am wanting to do is use the \A switch , I think, that will match only the start of the string. I have tried puting the switch in various places and don't seem to quit understand where it should go. I need an example :) Thanks for any help Larry pattern = re.compile(del_pattern) try: for each in os.listdir(file_location): if pattern.search(each): name = os.path.join(file_location, each) os.remove(name) except: type,value,tb = sys.exc_info() msgs.sendInfo(str(traceback.format_exception(type,value,tb) )) __________________________________ Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain information that is confidential privileged and/or exempt from disclosure under applicable law. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Thank you.

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IDLE question
by Dick Moores July 2, 2004

July 2, 2004

I'm trying to enter >>>if D.has_key("b"): print "yes" else: print "no" in IDLE v1.0.3. by typing it in, line by line. lines 1 and 2 go OK, but hitting "Enter" after "yes" causes the cursor to move to just under the "p" of "print", as expected. If I use the Backspace key and the space bar to line up and indent "else:" correctly, hitting Enter after that causes the error, "IndentationError: unindent does not match any outer indentation level (<pyshell#10>, line 3)". Is there no way to get this entered other than typing the 4 lines in a text editor and pasting them all together into IDLE? This is not an idle question. It's really been bugging me. ;-) Thanks, Dick Moores

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testing new style class properties using pyUnit ?
by Duncan Gibson July 1, 2004

July 1, 2004

I had a class which used get and set methods to access a class variable. I set up some unit tests using pyUnit. After some fiddling about, I managed to get it all working. I've just upgraded the source to use the new style classes with properties instead of explicit get and set methods. However, so far I've been unable to convert the unit tests. I note the error message, but I don't understand why. I include a simple example below, showing the working tests with the old style classes, and the failing tests with the new style classes. [In fact it's worse than this because my real code uses class variables and classmethods, and I want to test the derived classes, but the principle is the same] Can anyone explain the magical incantation that I need to test the property setter? Cheers Duncan #-------------------------------------------------- #!/usr/bin/env python2.3 import unittest #-------------------------------------------------- class A_Old: def __init__(self, x=0): self.x = x def get_x(self): return self.x def set_x(self, x): assert isinstance(x, int) self.x = x #-------------------------------------------------- class A_New(object): __slots__ = ('__x',) def __init__(self, x=0): self.x = x def __get_x(self): return self.__x def __set_x(self, x): assert isinstance(x, int) self.__x = x x = property(__get_x, __set_x) #-------------------------------------------------- class Test_A_Old(unittest.TestCase): def testGet(self): a = A_Old() self.assertEqual(0, a.get_x()) def testSet(self): a = A_Old() self.assertEqual(0, a.get_x()) self.assertEqual(None, a.set_x(1)) self.assertEqual(1, a.get_x()) def testSetFail(self): a = A_Old() self.assertEqual(0, a.get_x()) self.assertRaises(AssertionError, a.set_x, 1.0) #-------------------------------------------------- class Test_A_New(unittest.TestCase): def testGet(self): a = A_New() self.assertEqual(0, a.x) def testSet(self): a = A_New() self.assertEqual(0, a.x) self.assertEqual(None, a.__set_x(1)) # AttributeError: 'A_New' object has no attribute '_Test_A_New__set_x' self.assertEqual(1, a.x) def testSetFail(self): a = A_New() self.assertEqual(0, a.x) self.assertRaises(AssertionError, a.__set_x, 1.0) # AttributeError: 'A_New' object has no attribute '_Test_A_New__set_x' #-------------------------------------------------- unittest.main()

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strange listed nest behaviour
by Dave S July 1, 2004

July 1, 2004

I have a problem with lists, As an example the following makes sense to me and works as I would expect ... >>> b=[[0,0,0,0],[0,0,0,0]] >>> b [[0, 0, 0, 0], [0, 0, 0, 0]] >>> b[1][1]=5 >>> b [[0, 0, 0, 0], [0, 5, 0, 0]] >>> However I have to set up a large data list, so I have used "self.startslot=[[float(0)]*110]*36" inside a class. This is supposed to give me 0-35 lists each containing 0-109 floating point 0's which I can index into & change at will. This dos not perform as expected and one write causes the same data to be written to multiple locations. A more managable example being ... >>> a=[[float(0)]*10]*4 >>> a [[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]] >>> >>> a[1][1]=5 >>> >>> a [[0.0, 5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0], [0.0, 5, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]] >>> Printing 'a' gives the generated list as I would expect, but trying to write to one individual 'location' causes multiple 'locations' to be written to. (This caused me a headache before I twigged I can tell you :-) ) It must be something to do with the list definition but I am at a loss as to what is happening. Can anyone tell me what I am doing wrong ? Cheers Dave

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New Python user on board
by Bernard Lebel June 30, 2004

June 30, 2004

Hello, I wish to introduce myself, it is my first post on this mailing list. My name is Bernard Lebel, I'm from Montreal (Canada). I currently work in Marseille, France, as a rendering technical director (we are doing a full 3D animation feature film called "Magic Roundabout"). I'm already a JScript user and know VBScript to some capacity, because these two and Python (ActiveX enabled) are available in SOFTIMAGE|XSI (as well as PerlScript), the 3D animation software I use. At this point I'm very new to Python but I have read the tutorial in the documentation, it seems very promising. At this moment I'm mainly looking into Python to in hopes to develop a rendering management software. I apoligize in advance for the tons of newbie questions that will follow, and thank you in advance for your time. Bye Bernard

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help with regular expressions
by Jeff Peery June 30, 2004

June 30, 2004

hello I am having trouble with using the re module. I have a statement: line = FileHandle.readline(-1) test = findall('\d', line) where "line" is a line of text from a file I would like to read and extract numbers from. the line is simply three numbers, example 3.444456 4 84.3546354. I want to put these number in "test" but the findall expression seems to only take whole numbers, so for example test would be for the above numbers [3, 4, 4, 4, 4, 5, 6, 4, 8, ....]. How is this done so that test = [3.444456 4 84.3546354]? thanks. Jeff

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problem with format
by Ali Polatel June 30, 2004

June 30, 2004

Friends I have downloaded a calculator programme written in python from www.hotscripts.com ... When I open it with python I can only see its codes but I want to run the programme.How can i do this? Regards, --------------------------------- Do you Yahoo!? Yahoo! Mail - 50x more storage than other providers!

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Fastest way to write/read numerical data into/from a file?
by Karthikesh Raju June 30, 2004

June 30, 2004

Hi All, i have written a module that saves matrices in a file. Basically, a matrix as A = numarray.array([1,2]) will be saved as 1 2 in the file, and A = numarray.array([[1,2],[3,4]]) as 1 2 3 4 i.e each row is a line and there are spaces between each column. Presntly, when writing i do the following: try: i,j = data.shape for ii in range(0,i): for jj in range(0,j): value = "%s" %data[ii,jj] file.write(value) file.write(' ') file.write('\n') except ValueError: i = data.shape for ii in range(0,i): value = "%s" %data[ii] file.write(value) file.write(' ') file.write('\n') Here, i am doing an element by element access, how can i speed this up? While reading, i do the following: while(line): temp = [] list = string.split(line) for e in list: temp.append(string.atof(e)) x = numarray.concatenate(x,numarray.array(temp)) line = open1.readline() open1.close() So, while reading, i read a complete line, which i guess is faster, any suggestions on improving the speed esp when i am writing to the file. With warm regards karthik ----------------------------------------------------------------------- Karthikesh Raju, email: karthik(a)james.hut.fi Researcher, http://www.cis.hut.fi/karthik Helsinki University of Technology, Tel: +358-9-451 5389 Laboratory of Comp. & Info. Sc., Fax: +358-9-451 3277 Department of Computer Sc., P.O Box 5400, FIN 02015 HUT, Espoo, FINLAND -----------------------------------------------------------------------

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