Class Methods help
Hi, I have a question regarding the difference b/w "class methods" and "object methods". Consider for example: class MyClass: x = 10 Now I can access MyClass.x -- I want a similar thing for functions. I tried class MyClass: def some_func(x): return x+2 When I call MyClass.some_func(10) -- it fails, with error message: TypeError: unbound method some_func() must be called with MyClass instance as first argument (got int instance instead) OK. I figured out that something like this works: obj = MyClass() y = obj.some_func(10) BUT, this means that we have functions applying for instances. That is we have "instance method". Now, how do I implement some function which I can invoke with the class name itself ? Instead of creating a dummy object & then calling In short, how exactly do I create "class methods" ?? -- http://mail.python.org/mailman/listinfo/python-list
Integer dicision
How does (a/b) work when both 'a' and 'b' are pure integers ? >> (9/2) 4 >> (-9/2) -5 Why is it -5 ? I expect it to be -4 ? Because, in C/C++, 9/2 is 4 and so negative of it, (-9/2) is -4. What should I do to get C-like behavior ? -- http://mail.python.org/mailman/listinfo/python-list
Rounding a number to nearest even
The built-in function round( ) will always "round up", that is 1.5 is rounded to 2.0 and 2.5 is rounded to 3.0. If I want to round to the nearest even, that is my_round(1.5) = 2# As expected my_round(2.5) = 2# Not 3, which is an odd num I'm interested in rounding numbers of the form "x.5" depending upon whether x is odd or even. Any idea about how to implement it ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
On Apr 11, 3:27 pm, [EMAIL PROTECTED] wrote: > On 11 avr, 12:14, bdsatish <[EMAIL PROTECTED]> wrote: > > > The built-in function round( ) will always "round up", that is 1.5 is > > rounded to 2.0 and 2.5 is rounded to 3.0. > > > If I want to round to the nearest even, that is > > > my_round(1.5) = 2# As expected > > my_round(2.5) = 2# Not 3, which is an odd num > > > I'm interested in rounding numbers of the form "x.5" depending upon > > whether x is odd or even. Any idea about how to implement it ? > > When you say "round to the nearest even", you mean new_round(3) <> 3? No. not at all. The clause "nearest even" comes into picture only when a number is of form "x.5" or else it's same as builtin round( ). new_round(3.0) must be 3.0 itself. Here is the mathematical definition of what I want: If 'n' is an integer, new_round(n+0.5) = n if n/2 is integer new_round(n+0.5) = (n+1) if (n+1)/2 is integer In all other cases, new_round() behave similarly as round( ). Here are the results I expect: new_round(3.2) = 3 new_round(3.6) = 4 new_round(3.5) = 4 new_round(2.5) = 2 new_round(-0.5) = 0.0 new_round(-1.5) = -2.0 new_round(-1.3) = -1.0 new_round(-1.8) = -2 new_round(-2.5) = -2.0 The built-in function doesnt meet my needs for round(-2.5) or round(2.5) -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
On Apr 11, 4:37 pm, Scott David Daniels <[EMAIL PROTECTED]> wrote: > bdsatish wrote: > > The built-in function round( ) will always "round up", that is 1.5 is > def rounded(v): > rounded = round(v) > if divmod(v, 1)[1] == .5 and divmod(rounded, 2)[1] == 1: > if v > 0: > return rounded - 1 > return rounded + 1 > return rounded > > last = None > for n in range(-29, 28): > x = n * .25 > r = xr(x) > if r != last: > last = r > print > print '%s->%s' % (x, xr(x)), > Hi Scott, This is what I was looking for.. I forgot about divmod( ) thanks for reminding. -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
On Apr 11, 4:19 pm, [EMAIL PROTECTED] wrote: > couldn't you just do. > > #untested > new_round(n): > answer = round(n) > # is answer now odd > if answer % 2: > return answer - 1 > else: > return answer It fails for negative numbers: For -2.5 it gives -4.0 as answer whereas I expect -2.0 -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
On Apr 11, 4:24 pm, [EMAIL PROTECTED] wrote: > On Apr 11, 1:19 pm, [EMAIL PROTECTED] wrote: > > > couldn't you just do. > > > #untested > > new_round(n): > > answer = round(n) > > # is answer now odd > > if answer % 2: > > return answer - 1 > > else: > > return answer > > Whoops, this also affects odd numbers... > > Will try and find a GOOD solution later... > > Strange request though, why do you need it that way, because 2.5 is > CLOSER to 3 than to 2... It also fails for negative numbers. For -2.5 as input, I get -4.0 whereas I expect -2.0 This is a lengthy solution I came-up with: def round_even(x): temp = round(abs(x)) if (abs(x) - 0.5)%2.0 == 0.0: temp=temp-1 return signum(x)*temp def signum(x): if x>0: return 1 if x<0: return -1 return 0 But i guess there are better ways. I need it 'cos I'm translating some code from Mathematica to Python. And Math..ica's Round[ ] behaves this way (as I requested) -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
HI Gerard, I think you've taken it to the best possible implementation. Thanks ! On Apr 11, 5:14 pm, Gerard Flanagan <[EMAIL PROTECTED]> wrote: > In fact you can avoid the call to the builtin round: > > > def myround(x): > n = int(x) > if abs(x - n) >= 0.5 and n % 2: > return n + 1 - 2 * int(n<0) > else: > return n > > assert myround(3.2) == 3 > assert myround(3.6) == 4 > assert myround(3.5) == 4 > assert myround(2.5) == 2 > assert myround(-0.5) == 0.0 > assert myround(-1.5) == -2.0 > assert myround(-1.3) == -1.0 > assert myround(-1.8) == -2 > assert myround(-2.5) == -2.0 > -- http://mail.python.org/mailman/listinfo/python-list
Re: Rounding a number to nearest even
On Apr 11, 5:33 pm, bdsatish <[EMAIL PROTECTED]> wrote: > HI Gerard, > > I think you've taken it to the best possible implementation. Thanks ! > On Apr 11, 5:14 pm, Gerard Flanagan <[EMAIL PROTECTED]> wrote: > > > In fact you can avoid the call to the builtin round: > > > > > > assert myround(3.2) == 3 > > assert myround(3.6) == 4 > > assert myround(3.5) == 4 > > assert myround(2.5) == 2 > > assert myround(-0.5) == 0.0 > > assert myround(-1.5) == -2.0 > > assert myround(-1.3) == -1.0 > > assert myround(-1.8) == -2 > > assert myround(-2.5) == -2.0 > > OK, I was too early to praise Gerard. The following version: def myround(x): n = int(x) if abs(x - n) >= 0.5 and n % 2: return n + 1 - 2 * int(n<0) else: return n of Gerard doesn't work for 0.6 (or 0.7, etc.) It gives the answer 0 but I would expect 1.0 ( because 0.6 doesn't end in 0.5 at all... so usual rules of round( ) apply) -- http://mail.python.org/mailman/listinfo/python-list
Re: Java or C++?
On Apr 14, 12:21 pm, Bob Martin <[EMAIL PROTECTED]> wrote: > in 342367 20080414 074410 [EMAIL PROTECTED] wrote: > > >Hello, I was hoping to get some opinions on a subject. I've been > >programming Python for almost two years now. Recently I learned Perl, > >but frankly I'm not very comfortable with it. Now I want to move on > >two either Java or C++, but I'm not sure which. Which one do you think > >is a softer transition for a Python programmer? Which one do you think > >will educate me the best? > Certainly Java. It's also easier to find Java jobs than C++ jobs. -- http://mail.python.org/mailman/listinfo/python-list
restructured text in python
Hi all, I have a python prog: #!/usr/bin/env """ Author: BDS Version: 1.0 """ def Hello(): """ Prints a Hello World to the screen""" print "Hello, World" if __name__ == "__main__": Hello() I want to use ReSt (reStructuredText) in my docstrings or comments. Any example of how to do it, w.r.t. above code ? Also how to invoke rst on the Python code to do the processing ? I know how to write in RST but I want to know how to process the resulting Python code -- http://mail.python.org/mailman/listinfo/python-list
