removing common elemets in a list

[saif.shakeel@gmail.com]

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.
Thanks

[Tim Golden]

Re: removing common elemets in a list

saif.shakeel@gm ail.com wrote:

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.

Is this a test? Why don't you want to use the set operator?
Anyway, you can just move things from one list into another
excluding those which are already moved:

<code>
numbers = [1, 2, 3, 3, 4, 4, 5]
unique_numbers = []
for n in numbers:
if n not in unique_numbers:
unique_numbers. append (n)

print unique_numbers
</code>

It won't be the fastest thing you could do, but it
does work. Using a dictionary would speed things up,
but then you're basically implementing a set using
a dictionary.

TJG

[Gary Herron]

Re: removing common elemets in a list

saif.shakeel@gm ail.com wrote:

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.
Thanks
>
>

Several ways, but probably not as efficient as using a set. (And why
don't you want to use a set, one wonders???)

>>l = [1,2,3,1,2,1]

Using a set:

>>set(l)

set([1, 2, 3])



Building the list element by element:

>>for e in l:

.... if e not in r:
.... r.append(e)
....

>>print r

[1, 2, 3]



Using a dictionary:

>>d = dict(zip(l,l))
>>d

{1: 1, 2: 2, 3: 3}

>>d.keys()

[1, 2, 3]

>>>

[Carsten Haese]

Re: removing common elemets in a list

On Tue, 2007-05-15 at 23:17 -0700, saif.shakeel@gm ail.com wrote:

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.
Thanks

If the list is sorted, you can weed out the duplicates with
itertools.group by:

>>import itertools
>>L = [1,2,3,3,4,4,5]
>>[k for (k,_) in itertools.group by(L, lambda x:x)]

[1, 2, 3, 4, 5]

HTH,

--
Carsten Haese

http://informixdb.sourceforge.net

[John Zenger]

Re: removing common elemets in a list

On May 16, 2:17 am, saif.shak...@gm ail.com wrote:

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.
Thanks

Submit this as your homework answer -- it will blow your TA's mind!

import base64
def uniq(v):
return
eval(base64.b64 decode('c29ydGV kKGxpc3Qoc2V0KH YpKSxrZXk9bGFtY mRhIHg6di5pbmRl eCh4KSk='),loca ls())

[Michael Bentley]

Re: removing common elemets in a list


On May 16, 2007, at 10:36 AM, John Zenger wrote:

On May 16, 2:17 am, saif.shak...@gm ail.com wrote:

>Hi,
> Suppose i have a list v which collects some numbers,how do i
>remove the common elements from it ,without using the set() opeartor.
> Thanks

>
Submit this as your homework answer -- it will blow your TA's mind!
>
import base64
def uniq(v):
return
eval(base64.b64 decode
('c29ydGVkKGxpc 3Qoc2V0KHYpKSxr ZXk9bGFtYmRhIHg 6di5pbmRleCh4KS k='),local
s())

Nice! But I think he said he couldn't use set() ;-)

[janislaw]

Re: removing common elemets in a list

On May 16, 8:17 am, saif.shak...@gm ail.com wrote:

Hi,
Suppose i have a list v which collects some numbers,how do i
remove the common elements from it ,without using the set() opeartor.
Thanks

There was a similar thread on polish python newsletter. The following
post displays 4 different approaches and explores timings:

http://groups.google.com/group/pl.comp.lang.python/msg/dc3618b18e63f3c9

Fortunately, python code is universal.