Re: [Tutor] Parsing RSS Feeds

[Nitin Das]

http://www.feedparser.org/

--nitin

On Mon, Aug 16, 2010 at 3:50 AM, aug dawg  wrote:

> Hey all,
>
> Does anyone know of any modules to help my program parse RSS feeds?
>
> Thanks!
>
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Re: [Tutor] reading from 2 file output to 1

[Nitin Das]

I think in both the while loops , for loops are iterating over the new
lines, as a result col1,col2,col3,col4,col5,col6,col7 as a result after both
the while loop finishes these colums would only be having the values of the
last lines from both the files. as a result the new file3 would only be
having last lines of the both the files appended together, because u r
combining the columns after both the while loops.

--nitin

On Tue, Aug 17, 2010 at 2:09 PM, nitin chandra wrote:

> Hello All,
>
> I am trying to read from 2 CSV files, where first 4 ([0,1,2,3])
> columns are read from 'file1' and 3 columns ([1,2,3]) from 'file2' and
> write them into a 3rd file 'file3', 7 columns string. The data is
> Numeric values both, +ve and -ve.
>
> this is how i was trying.
>
> **
> import sys,os, fileinput
>
>
> file11 = raw_input('Enter PR1 File name :')
> fp1 = open(file11,'r')
>
> file12 = raw_input('Enter PR3 File Name :')
> fp2 = open(file12,'r')
>
>
> while 1:
>fp1 = fp1.readline()
>  for line in fp1:
> line2 = line.split(",")
> col1 = line2[0]
> col2 = line2[1]
> col3 = line2[2]
> col4 = line2[3]
> print col1
> print col2
> FL1 = '%s,%s,%s,%s' % (col1,col2,col3,col4)
> print FL1
>
> while 1:
>fp2 = fp2.readline()
>   for line1 in fp2:
>  line3 = line1.split(",")
>  col5 = line3[1]
>  col6 = line3[2]
>  col7 = line3[3]
>
>  FL2 = '%s,%s,%s,' % (col5,col6,col7)
>  print FL2
>
> file3=raw_input('Enter PR2 OUTPUT File Name :')
> fp3 = open(file3,'w')
>
> print col1,col2,col3,col4 + ',' + col5,col6,col7
>
> str3 = '%s,%s,%s,%s,%s,%s,%s\n' % (col1,col2,col3,col4,col5,col6,col7)
> fp3.write(str3)
>
> **
>
> I am getting the following error :
>
> Traceback (most recent call last):
>  File "mer5Pr2.py", line 16, in 
>col2 = line2[1]
> IndexError: list index out of range
>
> *
>
> There is data in the file at 'col2'. So what am i missing / doing wrong ?
>
> And is there better / optimized way of doing it?
>
> Thanks
>
> Nitin
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Re: [Tutor] Getting confusing NameError

[Nitin Das]

use raw_input instead of input . as using input is unsafe as it evaluates
your input as python command.
for e,g.
x = input("enter command") and u entered "1 + 2" as input., then it will
evaluate 1+2 = 3 = x.

 -nitin

On Wed, Aug 18, 2010 at 12:45 PM, shane brennan wrote:

> Hi Tutors
>
> This is my first mail to this list so firstly thank you for reading and
> apologies in advance for any noob mistakes i may have inadvertantly made:).
> Ive only started learning python as my first programming language and its
> all going well so far, working my way through a couple of books one of which
> is programming python: for absolute beginners by Michael Dawson
>
> In one of the code samples he supplies while doing loops ( namely if and
> else loops) im getting a NameError i dont understand and cannot find any
> help anywhere about it. here is the code he supplied and the error im
> getting
>
> # Password
> # Demonstrates the if statement
>
> print("Welcome to System Security Inc.")
> print("-- where security is our middle name\n")
>
> password = input("Enter your password: ")
>
> if password == "secret":
> print("Access Granted")
>
> input("\n\nPress the enter key to exit.")
>
>
> and the traceback error im getting
>
> Traceback (most recent call last):
>   File "G:\Programming\Python\programming python\chapter3\password.py",
> line 7,
> in 
> password = input("Enter your password: ")
>   File "", line 1, in 
> NameError: name 'secret' is not defined
>
>
> I know this is probably very simple but for some reason i cannot get my
> head around it.
>
> thank you for any help in advance
>
> shane
>
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[Tutor] Immutable objects

[Nitin Das]

Hello,

 Can somebody help me how to make immutable objects in python. I have
seen overriding the __new__, __setattr__ methods.. but not comfortable with
how to use them to make the object immutable.

thanks in advance
--nitin
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Re: [Tutor] Immutable objects

[Nitin Das]

class mymut(object):

  def __setattr__(self,k,v):
  if hasattr(self,k):
  if self.__dict__.get(k) == None:
  self.__dict__[k] = v
  else:
  raise TypeError("Cant Modify Attribute Value")
  else:
  raise TypeError("Immutable Object")


class mm(mymut):
x = ''
y = ''
def __init__(self,x,y):
self.x = x
self.y = y



p = mm(10,11)
print p.x
print p.y


I have created this immutable object.Is there any other better
implementation?

thanks
-- nitin




On Thu, Aug 19, 2010 at 8:54 AM, Nitin Das  wrote:

> Hello,
>
>  Can somebody help me how to make immutable objects in python. I have
> seen overriding the __new__, __setattr__ methods.. but not comfortable with
> how to use them to make the object immutable.
>
> thanks in advance
> --nitin
>
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Re: [Tutor] Immutable objects

[Nitin Das]

Thanks guys,
NamedTuple implementation is preety nice solution.

--nitin

On Thu, Aug 19, 2010 at 6:28 PM, Peter Otten <__pete...@web.de> wrote:

> Peter Otten wrote:
>
> > Nitin Das wrote:
> >
> >> class mymut(object):
> >>
> >>   def __setattr__(self,k,v):
> >>   if hasattr(self,k):
> >>   if self.__dict__.get(k) == None:
> >>   self.__dict__[k] = v
> >>   else:
> >>   raise TypeError("Cant Modify Attribute Value")
> >>   else:
> >>   raise TypeError("Immutable Object")
> >>
> >>
> >> class mm(mymut):
> >> x = ''
> >> y = ''
> >> def __init__(self,x,y):
> >> self.x = x
> >> self.y = y
> >>
> >>
> >>
> >> p = mm(10,11)
> >> print p.x
> >> print p.y
> >>
> >>
> >> I have created this immutable object.Is there any other better
> >> implementation?
> >
> > How about
> >
> >>>> from collections import namedtuple
> >>>> Mm = namedtuple("Mm", "x y")
> >>>> p = Mm(10, 11)
> >>>> p.x
> > 10
> >>>> p.y
> > 11
> >>>> p.x = 42
> > Traceback (most recent call last):
> >   File "", line 1, in 
> > AttributeError: can't set attribute
> >>>> p.z = 42
> > Traceback (most recent call last):
> >   File "", line 1, in 
> > AttributeError: 'Mm' object has no attribute 'z'
> >>>>
>
> By the way, you can see the class definition with
>
> namedtuple("Mm", "x y", verbose=True)
>
> Peter
>
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Re: [Tutor] List comprehension for dicts?

[Nitin Das]

result = [i%2 for i in itertools.takewhile(lamda x:i<  10, seq)]
is a good approach but it is taking little more time than the for loop over
iterator.

def takewhile(predicate, iterable):
# takewhile(lambda x: x<5, [1,4,6,4,1]) --> 1 4
for x in iterable:
if predicate(x):
yield x
else:
break

I don't know why? As it seems that this for loop and the other for loop
doing the same thing.

--nitin


On Fri, Aug 20, 2010 at 9:17 PM, bob gailer  wrote:

>  On 8/20/2010 5:44 AM, Steven D'Aprano wrote:
>
>> On Fri, 20 Aug 2010 06:10:59 pm Alan Gauld wrote:
>>
>>> "Steven D'Aprano"  wrote
>>>
>>>  the purpose). No matter how fast you can perform a loop, it's
 always faster to avoid it altogether, so this:

 seq = xrange(1000)
 result = []
 for i in seq:
if i>= 10: break
result.append(i%2)


 will be much faster than this:

 seq = xrange(1000)
 result = [i%2 for i in seq if i<  10]

>>> Although it should be pointed out that these are doing very different
>>> things.
>>>
>> Well yes, but I pointed out that you *can* bail out early of for-loops,
>> but not list comprehensions. The whole point is with a list comp,
>> you're forced to iterate over the entire sequence, even if you know
>> that you're done and would like to exit.
>>
>>  Take a look at itertools.takewhile!
>
> result = [i%2 for i in itertools.takewhile(lamda x:i<  10, seq)]
>
>
>
> --
> Bob Gailer
> 919-636-4239
> Chapel Hill NC
>
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Re: [Tutor] prime test problem

[Nitin Das]

For this problem u will get lots of solutions on the net.
e.g wilson's theorem , sieve of eranthoses etc.

--nitin

On Sat, Aug 21, 2010 at 7:05 PM, Roelof Wobben  wrote:

>  Hello,
>
> I have to make a programm which can test if a number is a prime.
> I know a prime is a number which can only be diveded by 1 and itself.
>
> One way is was thinking about is to make a loop which try if % has output
> 0.
> But that don't work.
>
> Can someone give me a hint what's the best approach is.
>
> Roelof
>
>
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Re: [Tutor] check the terminal keyword

[Nitin Das]

You can use raw_input like for e.g.
u_input = raw_input("user_command")
n then u can check u_input against anything. if doesn't matches then u can
throw an error.
I hope it shall help you.

--nitin


On Sat, Aug 21, 2010 at 6:37 PM, ANKUR AGGARWAL wrote:

> i m making a app in which i launch application using os.system("input from
> user"). I want to check whether the input entered by the user matches with
> the exact keyword in terminal or not.
> like i want to launch vlc so user should provide me input as " vlc" in
> order to launch the app just like he did from terminal. I want to make a
> check on the input spell so that if he type "wlc" it shows an error to it. I
> have an little idea abt sys.agrv but don't know how to use it... Plz help me
> guys.
> Thanks in advance
>
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Re: [Tutor] Adding all numbers in a file or list

[Nitin Das]

alternatively you can use the lambda , reduce function for summing up all
the numbers in a list for e.g:-

lis = [1,2,3,4,5]

p = reduce(lambda x,y : x+y, lis)

p will have the value = 15.


--nitin

On Mon, Aug 23, 2010 at 9:05 PM, aug dawg  wrote:

> Oh okay, sorry about that.
>
> Thanks for the help!
>
>
>
> On Mon, Aug 23, 2010 at 11:33 AM, Sander Sweers 
> wrote:
>
>> On 23 August 2010 17:24, aug dawg  wrote:
>> > So it's sum(list_name) ?
>>
>> Correct, but it is not limited to lists. Any itterable with
>> ints/floats will do, for example a tuple is also accepted.
>>
>> Greets
>> Sander
>>
>> PS: Please use reply to all so others on this list may benefit from
>> the questions/answers ;-)
>>
>
>
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Re: [Tutor] continuous running of a method

[Nitin Das]

The problem with this while loop is if your random value doesn't lie between
the mentioned range then ur 100% cpu would be utilized. The one thing u can
do is to sleep for some time lets say 0.5 sec after every while loop
iteration , in this case ur cpu utilization will go down.

--nitin

On Mon, Aug 23, 2010 at 8:21 PM, bob gailer  wrote:

>  On 8/23/2010 1:00 AM, Greg Bair wrote:
>
>> I have a method (I'll call it foo) that will either return None or an
>> object depending on a random value generated.  What I want to happen is that
>> if I call foo(), i.e, f = foo() and it returns None, to re-call it until it
>> returns something else.  I would think this would be done with a while loop,
>> but can't seem to get the details right.
>>
>
> Even though a while will work, you will have tied up the CPU until the loop
> terminates. This is never a good idea.
>
> What is your higher level goal?
>
>
> --
> Bob Gailer
> 919-636-4239
> Chapel Hill NC
>
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Re: [Tutor] Trouble with exercise regarding classes

[Nitin Das]

There are 2 ways to get the ypos value one is cball.ypos and another is
call.getY() both will give u the current ypos.

--nitin

On Thu, Aug 26, 2010 at 7:26 AM, Andrew Martin wrote:

> All I want to do is add a line that displays that maximum height the
> cannonball reaches. I created a variable zenith to store the highest y
> value. I then wanted to compare the current y value of the cannonball to
> zenith while the cannonballs y value is greater than zero. If the
> cannonballs current y value is greater than zenith, I want to have the
> current value replace zenith. Finally, once the cannonball has reaches y =
> 0, I wanted the program to write out the value for zenith.
>
> I want to compare zenith, a floating point number, with the current y
> value? I thought the current y value could be retrieved by Projectile.getY.
> And how do I call the getY using the instance?
>
>
>
>
> On Wed, Aug 25, 2010 at 7:24 PM, Alan Gauld wrote:
>
>>
>> "Andrew Martin"  wrote
>>
>>
>>  However, when I did so I got this error: "TypeError: unbound method
>>> getY()
>>> must be called with Projectile instance as first argument (got nothing
>>> instead) "
>>>
>>
>>  def main():
angle, vel, h0, time = getInputs()
cball = Projectile(angle, vel, h0)

>>>
>> cball is a Projectile instance
>>
>>
>> zenith = 0.0
while cball.getY() >= 0:

>>>
>> So this is fine
>>
>>
>> cball.update(time)

>>>
>>
>> if Projectile.getY > zenith:
zenith = Projectile.getY()

>>>
>> But what are you doing here?
>> You are trying to compare the getY method of the class with a floating
>> point number?
>> Then you call getY using the class rather than the instance?
>> I'm confused - and so is Python...
>>
>>
>> --
>> Alan Gauld
>> Author of the Learn to Program web site
>> http://www.alan-g.me.uk/
>>
>>
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Re: [Tutor] question about lists and doctest

[Nitin Das]

The doctest module searches for pieces of text that look like interactive
Python sessions, and then executes those sessions to verify that they work
exactly as shown.
Here ur a_list[3] in docstring is 42 then doctest expects it to be 42 for
success. Since u changed 42 to 16 then it is not = 42 as per the
a_list[3]=42 in docstring hence it raises error.

--nitin

On Thu, Aug 26, 2010 at 9:11 PM, Roelof Wobben  wrote:

>  hello,
>
> I have this programm
>
> #  Add your doctests here:
> """
>   >>> a_list[3]
>   42
>   >>> a_list[6]
>   'Ni!'
>   >>> len(a_list)
>   8
> """
> a_list = ['test', 'test','test',42,'test','test','Ni!','test']
> print a_list[3]
> print a_list[6]
> print len(a_list)
> if __name__ == '__main__':
> import doctest
> doctest.testmod()
>
> If I change lets say 42 to 16 then the doctest fails with
>
> Expecting
>
> 42
>
> Got
>
> 16.
>
>
> How does doctest now which values are right or not ?
>
> Roelof
>
>
>
>
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Re: [Tutor] import problem

[Nitin Das]

it is >>> import calendar not calender

--nitin

On Sat, Aug 28, 2010 at 10:51 PM,
wrote:

>
>
> tutor-bounces+christopher.henk=allisontransmission@python.org wrote on
> 08/28/2010 12:54:28 PM:
>
> > Hello,
> >
> > Im trying to do a import on a linux machine.
> > But now Im gettting this message :
> >
> > Python 2.6.5 (r265:79063, Apr  1 2010, 05:28:39)
> > [GCC 4.4.3 20100316 (prerelease)] on linux2
> > Type "help", "copyright", "credits" or "license" for more information.
> > >>> import calender
> > Traceback (most recent call last):
> >   File "", line 1, in 
> > ImportError: No module named calender
> > >>>
>
> Did you try calendar (with an 'a')?  it might have just been a spelling
> mistake in your import
>
> Can you do other imports from site-packages?
>
>
> Chris
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Re: [Tutor] function error

[Nitin Das]

It seems that ur turtle.position doesn't return a list because of this when
indexing is done on that u get this kind of error.

--nitin

On Tue, Sep 28, 2010 at 3:39 PM, Alan Gauld wrote:

>
> "roberto"  wrote
>
>
>  i have the following error when i call this function:
>>  20 def outOfBounds():
>> ---> 21 if abs(turtle.position()[0]) >
>> turtle.window_height()/2 or abs(turtle.position()[1]) >
>> turtle.window_width()/2:
>>22 return "true"
>>23 else:
>>
>> TypeError: 'function' object is unsubscriptable
>>
>> but i can't really figure out where is the problem with this function
>> 'unsubscriptable';
>>
>
> This means you are trying to use [] on a function.
> eg you might be doing turtle.position[1] instead of turtle.position()[1]
>
> I can't see it in your code sample but I'd check carefully that your
> parens() all balance correctly and are in the right place...
>
> HTH,
>
>
> --
> Alan Gauld
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
>
>
>
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