🌐 Mailman 3 May 2006 - Python-list - python.org

strip newlines and blanks
by micklee74＠hotmail.com May 2, 2006

May 2, 2006

hi i have a file test.dat eg abcdefgh ijklmn <-----newline opqrs tuvwxyz I wish to print the contents of the file such that it appears: abcdefgh ijklmn opqrs tuvwxyz here is what i did: f = open("test.dat") while 1: line = f.readline().rstrip("\n") if line == '': break print line but it always give me first 2 lines, ie abcdefgh ijklmn What can i do to make it print all w/o the newlines..? and what is the proper way to skip printing blank lines while iterating file contents? thanks

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Re: stripping
by Tim Williams May 2, 2006

May 2, 2006

On 1 May 2006 23:20:56 -0700, micklee74(a)hotmail.com <micklee74(a)hotmail.com> wrote: > > hi > i have a file test.dat eg > > abcdefgh > ijklmn > <-----newline > opqrs > tuvwxyz > <---newline > > > I wish to print the contents of the file such that it appears: > abcdefgh > ijklmn > opqrs > tuvwxyz > > here is what i did: > f = open("test.dat") > while 1: > line = f.readline().rstrip("\n") > if line == '': > break > #if not re.findall(r'^$',line): > print line > > but it always give me first 2 lines, ie > abcdefgh > ijklmn > > What can i do to make it print all..? The break is terminating the while loop after the first blank line, replacing it with a continue would solve the problem in your script. However: f = open("test.dat") while 1: line = f.readline().rstrip("\n") if line: print line is simpler and easier to read. And: >>> f = open("test.dat").read() # read the whole file at once into string f >>> print f.replace('\n\n','\n') abcdefgh ijklmn opqrs tuvwxyz >>> even simpler, as long as the file isn't huge. If you need the final newline removed, use: >>>print f.replace('\n\n','\n')[:-1] abcdefgh ijklmn opqrs tuvwxyz >>> HTH :)

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Non-web-based templating system
by qscomputing＠gmail.com May 2, 2006

May 2, 2006

Hi, I'm creating a small application in Python that uses lists and dictionaries to create a rudimentary database. I'd like to create some "fill-in-the-blanks" reports from this data, ideally by taking an RTF or plaintext file as a template and replacing placeholder tags with my data. Are there any good pre-written systems that would allow me to do this? Thanks, - QS Computing.

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returning none when it should be returning a list?
by randomtalk＠gmail.com May 2, 2006

May 2, 2006

hello, i have another problem i feel that i have to be missing something.. Basically, i've written a recursive function to find all the prime up to a number (lim).. here is the function: The function basically takes in a list of all the prime number found, it takes the next number to be tested for (next) and the limit it will go up to. It divide next by the list of previous prime numbers if next is not bigger than lim, count up all the times where it's not evenly divdided, if the result is equal the length of prime number, then we have another prime number, lather rinse and repeat :) def findPrime(seed, next, lim): print("seed: " + str(seed) + " next: " + str(next) + " lim: " + str(lim)) print(seed) if(next >= lim): print(seed) return seed else: count = 0; for num in seed: modu = math.modf(float(next)/float(num)); if(modu[0] > 0): count += 1 if(count == len(seed)): seed.append(next) findPrime(seed, next+2, lim) else: findPrime(seed, next+2, lim) As you can probably see, i've printed the value of seed up until the point where i'm returning the seed, however, the function still returns None..

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Re: Using elementtree: replacing nodes
by André May 2, 2006

May 2, 2006

Fredrik Lundh wrote: > André wrote: > > > I've started using elementtree and don't understand how to use it to > > manipulate and replace nodes. [snip] It was mostly the following step which I couldn`t figure out... > # 2) mutate the pre element > pre.clear() > pre.tag = "form" > pre[:] = [form] > [snip] > another approach is to build a parent map; see the parent_map code > at > > http://effbot.org/zone/element.htm#the-element-type > Thanks! > </F>

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resume picking items from a previous list
by kpp9c May 2, 2006

May 2, 2006

I have a several list of songs that i pick from, lets, say that there are 10 songs in each list and there are 2 lists. For a time i pick from my songs, but i only play a few of the songs in that list... now my wife, Jessica Alba, comes home, and i start playing from Jessica's list of songs. After playing a few songs, Jessica, who needs her beauty sleep, goes to bed, and i start my play loop which starts picking from my songs again... The wrinkle: only now i want it to pick first from among the 6 songs yet not played from the first time around, and *then* when the list is exhausted, shuffle the whole original list of songs and start again. Here is some working but hilariously bad code that does most of this funny biz... I've gotten this far, but can't figure out how to get the loops to keep track of what was played and what wasn't and how to pick-up the list where it left off. I know this is a dumb thing to want to do, but you know, being married to bona-fide star is not easy. # ----------------------------------------------------------- #!/usr/bin/env python import random import os def shuffleloop(iterable): """An iterator like itertools cycle, which returns elements from the iterable and saves a copy of each. When the iterable is exhausted, it return elements from the saved copy. The added wrinkle here is that the saved copy is randomly shuffled. Repeats indefinitely.""" saved = [] for element in iterable: yield element saved.append(element) while saved: random.shuffle(saved) for element in saved: yield element def playall_reload(startime, playdur, smpl_lst): '''a loop that shuffles and plays all sounds in a list. If the sequence is exhausted the list is reloaded, re-shuffled, and plyed through again. It does this as many times as needed to fill the time specified. Also returns the end of the last duration so that the begining of the next section can be fed to the next function or loop. ''' event = 0; incr = 0; lst_len = len(smpl_lst) random.shuffle(smpl_lst) smpl_loop = shuffleloop(smpl_lst) endpoint = startime + playdur while startime < endpoint: sample = smpl_loop.next() splt = os.path.split(sample) # get the duration of the current soundfile # (hard wire it for now) #incr = DUR() dur = 10 #load the sample & play it # # input(sample) # PLAY(startime, dur) # print "event %d @ %.4f --> [%s] dur: %.4f" % (event+1, startime, splt[1], dur) incr = dur startime = startime + incr event = event + 1 if (event < lst_len): print "\n\n*** Heads-up yo: <the input sequence was not exhausted> ***\n\n" return startime def test(): kevins = ['/Users/kevin/snd/songs/loveisintheair.aif', '/Users/kevin/snd/songs/boymeetsgirl.aif', '/Users/kevin/snd/songs/yourcheatingheart.aif', '/Users/kevin/snd/songs/kindletheflame.aif', '/Users/kevin/snd/songs/mywifeissohot.aif', '/Users/kevin/snd/songs/haha.aif', '/Users/kevin/snd/songs/blueberryorstrawberry.aif', '/Users/kevin/snd/songs/didyoupaytheelectricbill.aif', '/Users/kevin/snd/songs/whereistheremote.aif', '/Users/kevin/snd/songs/youspenthowmuchforthoseshoes.aif'] jessicas = ['/Users/kevin/snd/quiet_songs/iloveu.aif', '/Users/kevin/snd/quiet_songs/uloveme.aif', '/Users/kevin/snd/quiet_songs/wearehappy.aif', '/Users/kevin/snd/quiet_songs/wearesad.aif', '/Users/kevin/snd/quiet_songs/letsbreakup.aif', '/Users/kevin/snd/quiet_songs/letsgetbacktogether.aif', '/Users/kevin/snd/quiet_songs/walkinthesunshine.aif', '/Users/kevin/snd/quiet_songs/iloveutruly.aif', '/Users/kevin/snd/quiet_songs/whosefootisthat.aif', '/Users/kevin/snd/quiet_songs/ohbaby.aif'] print one = playall_reload(1.00, 20.00, kevins) print two = playall_reload(one, 180, jessicas) print three = playall_reload(two, 40.00, kevins) if __name__ == '__main__': test()

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Re: noob question: "TypeError" wrong number of args
by Edward Elliott May 2, 2006

May 2, 2006

Steve Holden wrote: > Objects don't actually "pass references to themselves". The interpreter > adds the bound instance as the first argument to a call on a bound method. Sure, if you want to get technical For that matter, objects don't actually call their methods either -- the interpreter looks up the method name in a function table and dispatches it. I don't see how shorthand talk about objects as actors hurts anything unless we're implementing an interpreter. > Sorry, it's a wart on your brain. Fine it's a wart on my brain. It's still a wart. > Read Guido's arguments in favor of an > explicit self argument again before you assert this so confidently. I would if I could find it. I'm sure he had good reasons, they may even convince me. But from my current perspective I disagree. > It's > certainly confusing to beginners, but there are actually quite sound > reasons for it (see next paragraph). While confusion for beginners is a problem, that's not such a big deal. It's a trivial fix that they see once and remember forever. What I mind is its ugliness, that the language makes me do work declaring self when it knows damn well it won't like my code until I do what it wants (yes I'm anthropomorphizing interpreters now). The interpreter works for me, I don't work for it. Things it can figure out automatically, it should handle. > Hmm. I see. How would you then handle the use of unbound methods as > first-class objects? If self is implicitly declared, that implies that > methods can only be used when bound to instances. I fail to see the problem here. I'm taking about implicit declaration on the receiving end. It sounds like you're talking about implicit passing on the sending end. The two are orthogonal. I can declare def amethod (a, b): and have self received implicitly (i.e. get the object instance bound by the interpreter to the name self). The sender still explicitly provides the object instance, e.g. obj.amethod (a,b) or class.amethod (obj, a, b) IOW everything can still work exactly as it does now, only *without me typing self* as the first parameter of every goddamn method I write. Does that make sense? > How, otherwise, would > you have an instance call its superclass's __init__ method if it's no > longer valid to say > > myClass(otherClass): > def __init__(self): > otherClass.__init__(self) > ... > Like this: myClass(otherClass): def __init__(): otherClass.__init__(self) self is still there and still bound, I just don't have to type it out. The interpreter knows where it goes and what it does, automate it already! >> * technically modules may be objects also, but in practice you don't >> declare self as a parameter to module functions > > The reason you don't do that is because the functions in a module are > functions in a module, not methods of (some instance of) a class. > Modules not only "may be" objects, they *are* objects, but the functions > defined in them aren't methods. What, in Python, *isn't* an object? If it looks like a duck and it quacks like a duck... Functions and methods look different in their declaration but the calling syntax is the same. It's not obvious from the dot notation syntax where the 'self' argument comes from. Some interpreter magic goes on behind the scenes. Great, I'm all for it, now why not extend that magic a little bit further?

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Using elementtree: replacing nodes
by André May 2, 2006

May 2, 2006

I've started using elementtree and don't understand how to use it to manipulate and replace nodes. I know how to do this using a simple, but inefficient parser I wrote, but I'd rather learn to use a better tool - especially as it is to be added to the standard library. I'll use a simple, but representative example. Suppose I have the following text, where I inserted blank lines to isolate the part I want to manipulate. =================== <html> <body> <p> This is some text. </p> <pre class="text"> a = 6*7 print a </pre> <p> Done. </p> </body> </html> ==================== Now, I would like to find all <pre> tags of the "text" class and 1. change the class value 2. append another node ( <textarea> ) 3. surround the both nodes by a third one ( <form> ) ================== <html> <body> <p> This is some text. <p> <form> <pre class="text2"> a = 6*7 print a </pre> <textarea cols=80 name="code"> </textarea> <input type="submit"></input> </form> <p> Done. </p> </body> </html> =============== Any help would be appreciated. André

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blank lines representation in python
by micklee74＠hotmail.com May 2, 2006

May 2, 2006

hi what is the correct way to represent blank lines in python (while iterating a file) without regexp? I know one way is to use re.search((line,r'^$') to grab a blank line, but i wanna try not to use regexp... is it 1) if line == ''": dosomething() (this also means EOF right? ) 2) if line is None: dosomething() 3) if not line: dosomething() thanks

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Re: Popping from the middle of a deque + deque rotation speed
by Russell Warren May 1, 2006

May 1, 2006

> So does the speed of the remaining 0.001 cases really matter? Note > that even just indexing into a deque takes O(index) time. It doesn't matter as much, of course, but I was looking to make every step as efficient as possible (while staying in python). As to indexing into a deque being O(index)... I didn't realize that. It is certainly something to keep in mind, though... looping through the contents of a deque would obviously be a bad idea with this being the case! I wonder if the generator for the deque helps reduce this? Will check later. Proof of the O(n) for indexing into a deque (not that I doubted Tim #2! :)... >>> import timeit >>> s = "from collections import deque; d = deque(xrange(1000000))" >>> timeit.Timer(stmt="x=d[10000]", setup = s).timeit(number=100000) 0.14770257113683627 >>> timeit.Timer(stmt="x=d[100000]", setup = s).timeit(number=100000) 1.4016418287799155 Russ

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