Re: Printing with interspersed element
At 2008-10-30T21:10:09Z, "Paulo J. Matos" <[EMAIL PROTECTED]> writes: > Thanks for the tip but that has an issue when dealing with potentially > millions of objects. You are creating a string in memory to then dump > to a file [or screen] while you could dump to the file [or screen] as > you go through the original string. Right? How about: def alternator(lst, sep): for index, item in enumerate(lst): if index: yield sep yield item for item in alternator(list_of_objects, 10): print item, -- Kirk Strauser The Day Companies -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing with interspersed element
On Thu, 30 Oct 2008 16:40:17 -0500, Grant Edwards wrote:
> If you want to do it "on the fly", then try something like this:
>
> iter = [1,2,3,4,5].__iter__()
> sys.stdout.write(str(iter.next()))
> for n in iter:
> sys.stdout.write(',' +str(n))
Maybe without shadowing the built in `iter()` and without calling the
"magic method" directly:
iterator = iter([1, 2, 3, 4, 5])
Ciao,
Marc 'BlackJack' Rintsch
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Re: Printing with interspersed element
On Oct 30, 2:10 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote: > On Thu, Oct 30, 2008 at 8:42 PM, Arnaud Delobelle > > > > <[EMAIL PROTECTED]> wrote: > > On Oct 30, 8:07 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote: > >> Hi all, > > >> I guess this is a recurring issue for someone who doesn't really know > >> the python lib inside out. There must be a simple way to do this. > >> I have a list of objects [x1, x2, x3, ..., xn] and I have defined a > >> print method for them print_obj(). Now I want to print them > >> intersepersed by an element. > >> If I print [x1, x2, x3] interspersed by the element 10: > >> x1.print_obj() 10 x2.print_obj() 10 x3.print_obj() > > >> Now, the question is, what's the best way to do this? > > > Defining a print_obj() method is probably a bad idea. What if you > > want to print to a file for example? Instead you can define a > > __str__() method for your objects and then use the join() method of > > strings like this: > > > print ' 10 '.join(str(x) for x in lst) > > Thanks for the tip but that has an issue when dealing with potentially > millions of objects. You are creating a string in memory to then dump > to a file [or screen] while you could dump to the file [or screen] as > you go through the original string. Right? Then I hope you are using stackless, because you are going to stack overflow _way_ before you recurse 1 million times. def print_list(seq, sep=','): seq = iter(seq) print seq.next(), for item in seq: print sep, print item, print Matt -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing with interspersed element
On 2008-10-30, Paulo J. Matos <[EMAIL PROTECTED]> wrote:
> On Thu, Oct 30, 2008 at 8:42 PM, Arnaud Delobelle
><[EMAIL PROTECTED]> wrote:
>> On Oct 30, 8:07 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote:
>>> Hi all,
>>>
>>> I guess this is a recurring issue for someone who doesn't really know
>>> the python lib inside out. There must be a simple way to do this.
>>> I have a list of objects [x1, x2, x3, ..., xn] and I have defined a
>>> print method for them print_obj(). Now I want to print them
>>> intersepersed by an element.
>>> If I print [x1, x2, x3] interspersed by the element 10:
>>> x1.print_obj() 10 x2.print_obj() 10 x3.print_obj()
>>>
>>> Now, the question is, what's the best way to do this?
>>
>> Defining a print_obj() method is probably a bad idea. What if you
>> want to print to a file for example? Instead you can define a
>> __str__() method for your objects and then use the join() method of
>> strings like this:
>>
>> print ' 10 '.join(str(x) for x in lst)
>
> Thanks for the tip but that has an issue when dealing with potentially
> millions of objects. You are creating a string in memory to then dump
> to a file [or screen] while you could dump to the file [or screen] as
> you go through the original string. Right?
If you want to do it "on the fly", then try something like this:
iter = [1,2,3,4,5].__iter__()
sys.stdout.write(str(iter.next()))
for n in iter:
sys.stdout.write(',' +str(n))
--
Grant Edwards grante Yow! The SAME WAVE keeps
at coming in and COLLAPSING
visi.comlike a rayon MUU-MUU ...
--
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Re: Printing with interspersed element
On 30 Oct 2008, at 21:10, Paulo J. Matos wrote:
On Thu, Oct 30, 2008 at 8:42 PM, Arnaud Delobelle
<[EMAIL PROTECTED]> wrote:
On Oct 30, 8:07 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote:
Hi all,
I guess this is a recurring issue for someone who doesn't really
know
the python lib inside out. There must be a simple way to do this.
I have a list of objects [x1, x2, x3, ..., xn] and I have defined a
print method for them print_obj(). Now I want to print them
intersepersed by an element.
If I print [x1, x2, x3] interspersed by the element 10:
x1.print_obj() 10 x2.print_obj() 10 x3.print_obj()
Now, the question is, what's the best way to do this?
Defining a print_obj() method is probably a bad idea. What if you
want to print to a file for example? Instead you can define a
__str__() method for your objects and then use the join() method of
strings like this:
print ' 10 '.join(str(x) for x in lst)
Thanks for the tip but that has an issue when dealing with potentially
millions of objects. You are creating a string in memory to then dump
to a file [or screen] while you could dump to the file [or screen] as
you go through the original string. Right?
Why would you want to print millions of objects on the screen?
As for writing to a file, a million objects will probably mean a few
tens of million bytes which is not that much. Your proposed method
would not work as the python call stack would explode first. Here is
one that may meet your approval (it still requires a __str__ method on
your objects but you can adapt it easily):
def print_with_sep(sep, iterable, file=sys.stdout):
iterator = iter(iterable)
try:
file.write(str(iterator.next()))
for item in iterator:
file.write(sep)
file.write(str(item))
except StopIteration:
pass
# Use like this:
>>> print_with_sep(' 10 ', [obj1, obj2, obj3])
--
Arnaud
--
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Re: Printing with interspersed element
On 2008-10-30, Paulo J. Matos <[EMAIL PROTECTED]> wrote: >> print ' 10 '.join(str(x) for x in lst) > > Thanks for the tip but that has an issue when dealing with potentially > millions of objects. You are creating a string in memory to then dump > to a file [or screen] while you could dump to the file [or screen] as > you go through the original string. Right? Right, but your original post didn't specify that you had millions of items. The best solution for a few dozen or a few hundred items is often different the the best solution for millions of items. The more accurate your question, the more useful the replies. -- Grant Edwards grante Yow! I haven't been married at in over six years, but we visi.comhad sexual counseling every day from Oral Roberts!! -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing with interspersed element
On Thu, Oct 30, 2008 at 8:42 PM, Arnaud Delobelle <[EMAIL PROTECTED]> wrote: > On Oct 30, 8:07 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote: >> Hi all, >> >> I guess this is a recurring issue for someone who doesn't really know >> the python lib inside out. There must be a simple way to do this. >> I have a list of objects [x1, x2, x3, ..., xn] and I have defined a >> print method for them print_obj(). Now I want to print them >> intersepersed by an element. >> If I print [x1, x2, x3] interspersed by the element 10: >> x1.print_obj() 10 x2.print_obj() 10 x3.print_obj() >> >> Now, the question is, what's the best way to do this? > > Defining a print_obj() method is probably a bad idea. What if you > want to print to a file for example? Instead you can define a > __str__() method for your objects and then use the join() method of > strings like this: > > print ' 10 '.join(str(x) for x in lst) > Thanks for the tip but that has an issue when dealing with potentially millions of objects. You are creating a string in memory to then dump to a file [or screen] while you could dump to the file [or screen] as you go through the original string. Right? > HTH > > -- > Arnaud > > -- > http://mail.python.org/mailman/listinfo/python-list > > > -- Paulo Jorge Matos - pocmatos at gmail.com Webpage: http://www.personal.soton.ac.uk/pocm -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing with interspersed element
On Oct 30, 8:07 pm, "Paulo J. Matos" <[EMAIL PROTECTED]> wrote: > Hi all, > > I guess this is a recurring issue for someone who doesn't really know > the python lib inside out. There must be a simple way to do this. > I have a list of objects [x1, x2, x3, ..., xn] and I have defined a > print method for them print_obj(). Now I want to print them > intersepersed by an element. > If I print [x1, x2, x3] interspersed by the element 10: > x1.print_obj() 10 x2.print_obj() 10 x3.print_obj() > > Now, the question is, what's the best way to do this? Defining a print_obj() method is probably a bad idea. What if you want to print to a file for example? Instead you can define a __str__() method for your objects and then use the join() method of strings like this: print ' 10 '.join(str(x) for x in lst) HTH -- Arnaud -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing with interspersed element
On 2008-10-30, Paulo J. Matos <[EMAIL PROTECTED]> wrote: > Hi all, > > I guess this is a recurring issue for someone who doesn't really know > the python lib inside out. There must be a simple way to do this. > I have a list of objects [x1, x2, x3, ..., xn] and I have defined a > print method for them print_obj(). Now I want to print them > intersepersed by an element. > If I print [x1, x2, x3] interspersed by the element 10: > x1.print_obj() 10 x2.print_obj() 10 x3.print_obj() >>> ','.join([str(i) for i in [1,2,3,4]]) '1,2,3,4' >>> ','.join([i.__repr__() for i in [1,2,3,4]]) '1,2,3,4' >>> ','.join([str(i) for i in [1]]) '1' -- Grant Edwards grante Yow! What I want to find at out is -- do parrots know visi.commuch about Astro-Turf? -- http://mail.python.org/mailman/listinfo/python-list
