Mailman 3 April 2002 - Tutor

Creating typed files with Python, BeOS (OT)
by Charlie Clark May 12, 2002

May 12, 2002

>Dear Python people, > >How can you tell Python to make a simple text file or to make a kind of file >with your own kind of extension? I have looked around in books I have, and >online. I have only found stuff about how to open and close and recieve >input from. I don't know enough about file creation and operating systems >to know I guess how to tell Python to do it. Creating typed files depends on the operating system's support for file types. Extensions are not the same as file types!!! Python will let you create files with any name as long as it is allowd by the operating system: f = open("ourfile", "w") Giving textfiles a ".txt" extension is purely a convention required for primitive file systems such as FAT/ NTFS or Posix. Removing or changing the extension can make such files unreadable on that system. Some file systems such as the BFS provide sophisticated file typing and Python can hook into this. Bear in mind that this is platform specific The following code creates an e-mail file in BeOS from BeOS.fsattr import write_attr newfile = "newfile.mail" # creat an empty file f = open(newfile, "w") f.close() #give our new file a file type write_attr(newfile, "BEOS:TYPE", B_MIME_STRING_TYPE, "text/x-email\0", 0) Our file "newfile.mail" now has the MIME-type "text/x-email". E-mail files are a subset of textfiles and can be read by any text editor or mail program independent of the file extension. Charlie

3 2

Glade
by djuro m. May 7, 2002

May 7, 2002

Hello everyone! Could someone please "explain" to me how to make a simple gui working with python code by using Glade. ( I only need to see a code or how is python code tied with gui code file) I already tried several times according to instructions in available "Getting started-s" but it didn't work. I use RedHat 7.0, Python 1.5.2 and Glade 0.5.9 For example by Tkinter: from Tkinter import * top = Tk() e = Entry() e.pack() def Write(): global e m = "Hi there!" e.insert(END,m) b = Button(text='OK',command = Write) b.pack() top.mainloop() Thank you D. M.

6 5

Multifunction mapping
by Jordan, Jay May 4, 2002

May 4, 2002

how would it be possible to multi finction a map statement. Consider the following. I have a sequence of characters (a,b,c,d,e,f,g,h,i) I want to convert the whole list to their ascii codes (ord) (61,62,63,64,65,66,67,68,69) I want to zfill them all to three digits (061,062,063,064,065,066,067,068,069) and then concatenate the whole list into a single string (061062063064065066067068069) Can that be done with a single map statement? Python is such an elegant language for doing big complicated things with just a very few statements so I am certan there has to be a better way than running through the list one at a time or mapping, writing, mapping, writing, mapping, writing. Thanks Jay

6 5

A problem: scanning for keywords in a bunch of text?
by Danny Yoo May 2, 2002

May 2, 2002

Hi everyone, I have a small project that I've been working on. Being lazy, I thought it might be good to ask about it here and hear what people think. Part of this project involves scanning for a preprepared list of "keywords" though a lot of text. More specifically: I'm searching for biological terms in a huge collection of journal articles. ### >>> import MySQLdb >>> conn = MySQLdb.connect(db='pub2') >>> cursor = conn.cursor() >>> cursor.execute("select name from term") 46627L >>> def first(x): return x[0] ... >>> terms = map(first, cursor.fetchall()) >>> terms[:8] ['(+)-camphor metabolism', '(3R)-hydroxymyristol acyl carrier protein dehydratase', '(3\\,5-dichlorophenylurea)acetate amidohydrolase', '(delayed) early viral mRNA transcription', '(N-acetylneuraminyl)-galactosylglucosylceramide', '(R)-4-hydroxymandelate catabolism', '(R)-aminopropanol dehydrogenase', '(R)-mandelate catabolism to benzoate'] ### The one immediate problem I have is that I'm actually scanning through quite a few terms here. Another problem is that these keywords have spaces in them, and that can complicate things. (See: http://www.geneontology.org/ if you're wondering what these curious terms are about.) Python's regular expression engine might not be powerful enough to handle this in one big gulp: ### >>> import re >>> decorated_terms = map(re.escape, terms) >>> re.compile('|'.join(decorated_terms), re.IGNORECASE) <SRE_Pattern object at 0x403b0008> >>> big_pattern = re.compile('|'.join(decorated_terms), re.IGNORECASE) >>> >>> big_pattern.findall('''The activity of the Arabidopsis heat shock transcription factor (HSF) is repressed at normal conditions but activated by cellular stresses. Circumstantial evidence suggests that HSP70 may function as a negative feedback regulator of HSF activity. Here the interaction between HSF and HSP70 is reported using electrophoretic mobility shift and yeast two-hybrid assays. Subdomain mapping indicates an interaction of the activation domain and DNA-binding domain of HSF1 with HSP70.''') Traceback (most recent call last): File "<stdin>", line 1, in ? RuntimeError: internal error in regular expression engine ### Ouch. So if I really want to go through this with regular expressions, I'll probably need to break my set of keywords into smaller chunks that the expression engine can handle. But regular expressions are still too slow. I've tested a subset of the keywords on the text above, and it takes around 5 seconds to do a findall() scan across the test abstract above. This is not nearly fast enough: I need to be able to scan my documents in milliseconds. I actually don't use regular expressions at the moment: I've done something even sillier with "Suffix Trees": http://hkn.eecs.berkeley.edu/~dyoo/python/suffix_trees/ So I do have something that does work for the moment... but it's just not as straightforward as I'd like. Perhaps 'agrep' at: http://www.bio.cam.ac.uk/~mw263/pyagrep.html might help... Hmmm... In any case, I'm curious to hear suggestions on ways to simplify this problem. Thanks for any help!

2 2

A small math puzzle [recreational Python]
by Danny Yoo May 2, 2002

May 2, 2002

Hi everyone, I ran across this puzzle while browsing the the 'alt.math.undergrad' newsgroup. I thought it might make a fun programming exercise, so here's my paraphrase of the puzzle: A "rearrangement without fixed letters" of a given word is a mixup of the letters so that, if one were to overlap the original with the rearrangement, no letters should match. For example, given the word: 'TERESA' here are a two "rearrangements without fixed letters": ['RTESAE', 'SATREE'] However, here's an example that is a rearrangement but doesn't work because it has a fixed letter: 'TRESAE' ^ In this example, the 'T' makes this rearrangement inacceptable, since 'TERESA' itself begins with a 'T' too. The puzzle is to write a program that counts all the possible rearrangements without fixed letters. Have fun!

8 16

Re: Printable versions of "What's new" documents?
by Alexandre Ratti May 1, 2002

May 1, 2002

Hi Rogério, At 22:12 29/04/2002 -0400, you wrote: >Date: Mon, 29 Apr 2002 16:30:30 -0300 >From: Rogério Brito <linuxconsult(a)yahoo.com.br> >Subject: [Tutor] Printable versions of "What's new" documents? > I just finished reading the tutorial for version 2.0 of Python > and I saw that there are documents written by A.M. Kuchling > entitled "What's New in Python" for versions 2.0, 2.1 and 2.2. > I would like to read them in order to catch up with the > language improvements and also see a longer discussion on the > language. > > Unfortunately, while I found a Postscript version of the > document for version 2.2, I only found on-line versions of the > documents corresponding to versions 2.0 and 2.1. I only have PDF copies of these docs. If you can't use PDF, I can try outputting these docs to PS and put them somewhere for download. Let me know if you need them. Cheers. Alexandre

2 3

HP preinstalled Python!
by Lance E Sloan May 1, 2002

May 1, 2002

This weekend, my wife and I finally gave in and bought a Windows computer. Well, we've had one before, but we mostly used Macs and I use UNIX a lot. This is our first purchase of a brand-new, semi-beefy Windows computer. My wife wanted it to run certain programs that were only available for Windows and I figured it's best to "know thy enemy". So we bought an HP Pavilion 531w. It's not the most powerful machine, but good enough. So, as I was installing various apps, I discovered that in the "Program Files" directory, there is a Python directory. And there was also a TCL directory. Both of them apparently have working versions of those languages. I've not found anything in the documentation about them yet, but I figure that among the other third-party programs HP installed, there must be one that uses Python, probably with Tkinter. Has anybody else noticed this on new HP computers? -- Lance E Sloan Web Services, Univ. of Michigan: Full-service Web and database design, development, and hosting. Specializing in Python & Perl CGIs. http://websvcs.itd.umich.edu/ - "Putting U on the Web"

3 2

Re: [Tutor] more newbie questions
by urgrue May 1, 2002

May 1, 2002

>You can try <Ctrl+L> in command-line Python on *NIX OSes. is there no cross-platform alternative? well, i guess print "\n"*24 is fine, its just a bit sloppy. > >>> print "this", "is", "a", "test" >this is a test > >>> print "this" + "is" + "a" + "test" >thisisatest thanks, thats what i wanted indeed. but, how would this be done for example in this case: grid = [[1,2,3],[4,5,6],[7,8,9]] for row in grid: for column in row: print column, print now this does: 1 2 3 4 5 6 7 8 9 but i need: 123 456 789 thanks, fred

4 6

more newbie questions
by urgrue April 30, 2002

April 30, 2002

thanks to everyone who helped me out with my first post. i'm getting a python book today so hopefully then i'll have less to post about ;) just a couple little questions: 1. how to simply clear the screen? im using print "\n"*24 which works of course, but is a bit ugly. 2. how can i avoid every print statement forcing a space between what it prints?

2 1

How can I do IP_MASQ by using Python?
by Ares Liu April 30, 2002

April 30, 2002

I want to transfer MGCP packages via NAT. Not so much flux, so I think I can use python to do it. Does anyone can give me some advises? Regards Ares

3 5