🌐 Mailman 3 July 2008 - Python-list - python.org

Why is recursion so slow?
by slix July 1, 2008

July 1, 2008

Recursion is awesome for writing some functions, like searching trees etc but wow how can it be THAT much slower for computing fibonacci- numbers? is the recursive definition counting fib 1 to fib x-1 for every x? is that what lazy evaluation in functional languages avoids thus making recursive versions much faster? is recursive fibonacci in haskell as fast as an imperative solution in a procedural language? def fibr(nbr): if nbr > 1: return fibr(nbr-1) + fibr(nbr-2) if nbr == 1: return 1 if nbr == 0: return 0 def fibf(n): sum=0 a=1 b=1 if n<=2: return 1 for i in range(3,n+1): sum=a+b a=b b=sum return sum i found a version in Clojure that is superfast: (def fib-seq (concat [0 1] ((fn rfib [a b] (lazy-cons (+ a b) (rfib b (+ a b)))) 0 1))) (defn fibx [x] (last (take (+ x 1) fib-seq))) (fibx 12000) is delivered instantly. is it using lazy evaluation?

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Having problems using Tkinter
by viv1tyagi＠gmail.com July 1, 2008

July 1, 2008

Hi everyone ! ! ! I'm just a month old in the world of Python and trying to develop an application using Tkinter in which a new window pops out on a particular button press.The code for this new window is in "AddKlas.py" file. The problem is all the content of the new window is overwritten on the previous window. Below is the code of the two files PLEASE help me out ! ! ! ! #1st file #Klass.py from Tkinter import * import AddKlass class Klass(Frame): def __init__(self): self.labels() self.buttons() self.menubuttons() self.scrollandcanvas() def labels(self): label1=Label(relief='groove',text=" Class Id",width=20,anchor=W) label1.grid(row=0,column=0) label2=Label(relief='groove',text=" Class Name",width=20,anchor=W) label2.grid(row=0,column=1) label3=Label(relief='groove',text=" Class Room No.",width=20,anchor=W) label3.grid(row=0,column=2) label4=Label(relief='groove',text=" Category Id",width=80,anchor=W) label4.grid(row=0,column=3) def buttons(self): button1=Button(text="Add",width=10,command=self.CallAdd) button1.grid(row=2,column=5) button2=Button(text="View",width=10,state=DISABLED) button2.grid(row=3,column=5) button3=Button(text="Next",width=10,state=DISABLED) button3.grid(row=4,column=5) def menubuttons(self): menubutton=Menubutton(text="Options",width=10,relief="raised") menubutton.grid(row=5,column=5) menubutton.menu=Menu(menubutton) menubutton["menu"]=menubutton.menu menubutton.menu.add_command(label="Modify") menubutton.menu.add_command(label="Delete") def scrollandcanvas(self): yscroll=Scrollbar() yscroll.grid(row=1,column=4,rowspan=7,sticky=N+S) canva=Canvas(bg="#fff",yscrollcommand=yscroll.set) canva.grid(row=1,column=0,rowspan=7,columnspan=4,sticky=N+E+S +W) def CallAdd(self): AddKlass.root=Tk() AddKlass.AddKlas() AddKlass.root.focus_force() AddKlass.root.geometry("275x250") AddKlass.root.title("Add Class Information") AddKlass.root.resizable(width=False,height=False) AddKlass.root.mainloop() root=Tk() app = Klass() root.geometry("960x300") root.title("Class Information") root.resizable(width=False,height=False) root.mainloop() #2nd file #AddKlass.py from Tkinter import * class AddKlas(Frame): #root=None def __init__(self): self.labels() self.buttons() self.entry() def labels(self): label1=Label(relief='flat',text=" Class Id :",height=3,width=20) label1.grid() label2=Label(relief='flat',text=" Class Name :",height=3,width=20) label2.grid() label3=Label(relief='flat',text=" Class Room No. :",height=3,width=20) label3.grid() label4=Label(relief='flat',text=" Category Id :",height=3,width=20) label4.grid() def buttons(self): button1=Button(text="Add",width=10,state=DISABLED) button1.grid(row=5,column=0) button2=Button(text="Cancel",width=10,command=self.quit) button2.grid(row=5,column=1) def entry(self): entry1=Entry() #by default width =20 entry1.grid(row=0,column=1) entry2=Entry() entry2.grid(row=1,column=1) entry3=Entry() entry3.grid(row=2,column=1) entry4=Entry() entry4.grid(row=3,column=1) #root=Tk() #app = AddKlas() #root.geometry("275x250") #root.title("Add Class Information") #root.resizable(width=False,height=False) #root.mainloop()

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Create a sex site
by jinole July 1, 2008

July 1, 2008

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Naruto 407, One Piece 506, Bleach 329 Hot manga Download
by mangaboy001 July 1, 2008

July 1, 2008

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Functions associated with a class.
by Kurda Yon July 1, 2008

July 1, 2008

Hi, I start to learn the object oriented programing in Python. As far as I understood, every class has a set of corresponding methods and variables. For me it is easy to understand a method as a one-argument function associated with a class. For example, if I call "x.calc" and "y.calc" and if "x" and "y" belongs to different classes I, actually, call to different function (the first one is associated with the first class and the second one with the second class). If "x" and "y" belongs to the same class, the "x.calc" and "y.calc" refer to the same function (but called with different arguments ("x" and "y", respectively)). In the above described case we have one-argument function. But what should we do if we one two have a two-argument function. For example, we want to have a method "calc" which take two objects and returns one value. How do we call this method? Like "x&y.calc"? Or just calc(x,y)? In the case of the one-argument functions Pythons automatically decide which function to call (associated with the first class or with the second class). Will it be the same in the case of the two-argument function. I am not sure that I am clear. If I am not clear, just ask me. I will try to reformulate my questions. Thank you.

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Freeze problem with Regular Expression
by Kirk July 1, 2008

July 1, 2008

Hi All, the following regular expression matching seems to enter in a infinite loop: ################ import re text = ' MSX INTERNATIONAL HOLDINGS ITALIA srl (di seguito MSX ITALIA) una ' re.findall('[^A-Z|0-9]*((?:[0-9]*[A-Z]+[0-9|a-z|\-]*)+\s*[a-z]*\s*(?:[0-9] *[A-Z]+[0-9|a-z|\-]*\s*)*)([^A-Z]*)$', text) ################# No problem with perl with the same expression: ################# $s = ' MSX INTERNATIONAL HOLDINGS ITALIA srl (di seguito MSX ITALIA) una '; $s =~ /[^A-Z|0-9]*((?:[0-9]*[A-Z]+[0-9|a-z|\-]*)+\s*[a-z]*\s*(?:[0-9]*[A- Z]+[0-9|a-z|\-]*\s*)*)([^A-Z]*)$/; print $1; ################# I've python 2.5.2 on Ubuntu 8.04. any idea? Thanks! -- Kirk

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Re: how to judge urllib.Request is finished?
by Marc 'BlackJack' Rintsch July 1, 2008

July 1, 2008

On Tue, 01 Jul 2008 15:16:03 +0800, oyster wrote: > currently I am using > [code] > req=urllib2.Request(url) > data='' > if '</htm>' not in data: > fd=urllib2.urlopen(req) > data=fd.read() > time.sleep(10) > time.sleep(10) > blahblah > [/code] That looks very strange. Why the ``if`` and the `sleep()`\s? The ``if`` condition is always true, so it's completely unnecessary. The `read()` call is blocking, that means it returns iff the complete data is read. So there's no need to wait or to check if all is read. If there's a problem with the connection an exception should be raised by `urllib2`. Ciao, Marc 'BlackJack' Rintsch

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How make regex that means "contains regex#1 but NOT regex#2" ??
by seberino＠spawar.navy.mil July 1, 2008

July 1, 2008

I'm looking over the docs for the re module and can't find how to "NOT" an entire regex. For example..... How make regex that means "contains regex#1 but NOT regex#2" ? Chris

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how to judge urllib.Request is finished?
by oyster July 1, 2008

July 1, 2008

currently I am using [code] req=urllib2.Request(url) data='' if '</htm>' not in data: fd=urllib2.urlopen(req) data=fd.read() time.sleep(10) time.sleep(10) blahblah [/code] Is there any other ready-to-use function? And what if the internet connection is chocked so that the html page can not be loaded entirely?

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Are the following supported in scipy.sparse
by dingo_1980 July 1, 2008

July 1, 2008

I wanted to know if scipy.sparse support or will support the following functions which are available in scipy.linalg or scipy or numpy: Inverse Cholesky SVD multiply power append eig concatenate Thanks...

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