more efficient?
I have the following two implementation techniques in mind. def myfunc(mystring): check = "hello, there " + mystring + "!!!" print check OR structure = ["hello, there",,"!!!"] def myfunc(mystring): structure[2] = mystring output = ''.join(mystring) i heard that string concatenation is very slow in python; so should i go for the second approach? could someone tell me why? Would there be another 'best-practice-style'? Please help. Thankx in advance! cheers!!! Zubin -- http://mail.python.org/mailman/listinfo/python-list
Re: more efficient?
thank you for your help and support. i`ll keep your advice in mind. :) cheers!!! Zubin On Tue, Dec 22, 2009 at 8:07 PM, Lie Ryan wrote: > On 12/22/2009 5:13 PM, Zubin Mithra wrote: >> >> I have the following two implementation techniques in mind. >> >> def myfunc(mystring): >> check = "hello, there " + mystring + "!!!" >> print check >> >> >> OR >> structure = ["hello, there",,"!!!"] >> def myfunc(mystring): >> structure[2] = mystring >> output = ''.join(mystring) >> >> i heard that string concatenation is very slow in python; so should i >> go for the second approach? could someone tell me why? Would there be >> another 'best-practice-style'? >> Please help. Thankx in advance! > > Python's strings are immutable and to concatenate two string the interpreter > need to copy two whole string into a new string object. This isn't a > performance problem until you're trying to concatenate a list containing a > thousand strings: > ['abc', 'bcd', 'cde', 'def', ...] > with the naive approach: > joined = '' > for s in lst: > joined = joined + s > > first python will conc. '' and 'abc', copying 0+3 = 3 chars > then it conc. 'abc' and 'bcd', copying 3+3 = 6 chars > then it conc. 'abcbcd' and 'cde' copying 6+3 = 9 chars > then it conc. 'abcbcdcde' and 'def' copying 9+3 = 12 chars > and so on... > > for four 3-letter strings, python copies 3 + 6 + 9 + 12 = 30 chars, instead > of the minimum necessary 12 chars. It gets worse as the number of strings > increases. > > When you concatenate two 1000-chars large strings, both + and ''.join will > have to copy 2000 chars. But when you join one thousand 2-chars string > you'll need to copy 1001000 chars[!] with +. > > Now, early optimization *is evil*. Don't start throwing ''.join every here > and there. The performance by the concatenations won't start to matter until > you're concatenating a large lists (>40) and + is much more readable than > ''.join(). > > When concatenating small number of strings I preferred > %-interpolation/str.format; it's often much more readable than ''.join and > +. > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
code review
Hello, I`m pretty new to developing applications using python and i would like advance on this script i recently created which helps linux programmers on the linux terminal. The code is very simple to understand(i hope) and serves a simple purpose; however i am not sure if my way of scripting is the right "pythonic" way of doing it. The package can be found at www.code.google.com/p/pyautorun I`d love any feedback, ideas and criticism after a code review. Thank you in advance. cheers!!! Zubin Mithra -- http://mail.python.org/mailman/listinfo/python-list
socket programming
The code snippet i have pasted at, http://paste.pocoo.org/show/160555/ produces a traceback which also has been pasted at the above link. The snippet attempts at socket programming using OOPs concepts. Please help. Thankx in advance Zubin Mithra -- http://mail.python.org/mailman/listinfo/python-list
PyAutoRun
Hello, I have been using python for quite some time; however this is the first python project i have worked on. The code is hosted at http://github.com/zubin71/PyAutoRun The code needs re-factoring and feature additions; i have put up a TODO list there too. It`d be great if anyone could work on this; i intend to develop this further(with a bit of help) and will request for its addition into debian and ubuntu repositories, in time. Also, any kind of code-review, criticism, is also appreciated. However, it`d be awesome if you could just fork it at github, pull, modify and push. :) Have a nice day! cheers!!! Zubin -- http://mail.python.org/mailman/listinfo/python-list
D-Bus
Hello, I have experience writing scripts to connect to the D-Bus interface provided by different applications but have no experience writing a D-Bus interface for an application. Could someone point me in the right direction? A tutorial or a good example would be nice. Cheers!!! Zubin Mithra http://zubin71.wordpress.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Hwy doesn't len(None) return zero ?
On Thu, Jul 1, 2010 at 12:09 AM, Stef Mientki wrote: > hello, > > I've lot of functions that returns their result in some kind of tuple / > list / array, > and if there is no result, these functions return None. > Now I'm often what to do something if I've more than 1 element in the > result. > So I test: > >if len ( Result ) > 1 : > > But to prevent exceptions, i've to write ( I often forget) > if Result and ( len ( Result ) > 1 ) : > use if Result: Checking the length would be a bad idea. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Python for web applications
On Wed, Jun 30, 2010 at 11:34 PM, Wyatt Schwartz wrote: > Dear Python-List members, > > Sorry for asking such a simple (or possibly complicated) question, as I am > new to Python programming. Anyways, I have read online that many popular > websites use Python for some of their web-based applications (for example, > Reddit), and that lead me to wonder how is this done? > > Thanks in advance! > > I would recommend that you check out the various web-frameworks which are out there. Django is the framework I use and love, but there are loads out there. Have fun! Zubin -- http://mail.python.org/mailman/listinfo/python-list
Re: Composition of functions
Hello, >>> y=list(x).reverse() > >>> print y > None > >>> L = ["a", "b", "c"] >>> L.reverse() >>> L ["c", "b", "a"] As you can see, L.reverse() performs the operation on itself and returns nothing. Hence, the return type None. Instead of y=''.join(list(x).reverse()) you should probably do, >>> t = list(x).reverse() >>> y = ''.join(t) Cheers! Zubin -- http://mail.python.org/mailman/listinfo/python-list
Re: Composition of functions
> Er, I don't think you thought that one entirely through (/ tried it out): > > My Apologies. Here is a working one. >>> x="123" >>> t = list(x) >>> t.reverse() >>> print ''.join(t) 321 But of course, the method which was suggested earlier is far more elegant. >>> print ''.join(reversed(list(x))) Cheers! Zubin -- http://mail.python.org/mailman/listinfo/python-list
