any modules having a function to partition a list by predicateprovided?

[knifenomad]

i know it's not very hard to get that solution.
just by implementing simple function like below.

def partition(target, predicate):
"""
split a list into two partitions with a predicate
provided.
any better ideas?
"""
true = []
false= []
for item in target:
if predicates(item):
true.append(item)
else:
false.append(item)
return true, false

but i wonder if there's another way to do this with standard libraries
or .. built-ins.
if it's not, i'd like the list objects to have partition method like
string module has.

true, false = [1,2,3,4].partition(lambda x: x >1)

print true, false
[2,3,4] [1]

 

[Chris Rebert]

i know it's not very hard to get that solution.
just by implementing simple function like below.

     def partition(target, predicate):
           """
           split a list into two partitions with a predicate
provided.
           any better ideas?
           """
           true = []
           false= []
           for item in target:
               if predicates(item):
                   true..append(item)
               else:
                   false.append(item)
           return true, false

but i wonder if there's another way to do this with standard libraries
or .. built-ins.
if it's not, i'd like the list objects to have partition method like
string module has.

(A) str.partition() has a /completely/ different meaning from your partition()
(B) You'd probably have better luck getting it added to the itertools
module since the concept is applicable to all iterables.
[http://docs.python.org/library/itertools.html]

Cheers,
Chris

 

[segunai]

i know it's not very hard to get that solution.
just by implementing simple function like below.

     def partition(target, predicate):
           """
           split a list into two partitions with a predicate
provided.
           any better ideas?
           """
           true = []
           false= []
           for item in target:
               if predicates(item):
                   true.append(item)
               else:
                   false.append(item)
           return true, false

but i wonder if there's another way to do this with standard libraries
or .. built-ins.
if it's not, i'd like the list objects to have partition method like
string module has.

(A) str.partition() has a /completely/ different meaning from your partition()
(B) You'd probably have better luck getting it added to the itertools
module since the concept is applicable to all iterables.
[http://docs.python.org/library/itertools.html]

Cheers,
Chris
--http://blog.rebertia.com

yep, my mistake. i shouldn't have compared it to string's partition().
i just wanted that convenience string.partition() has as a built-in.
anyway, thanks for itertools.

 

[Krister Svanlund]

i know it's not very hard to get that solution.
just by implementing simple function like below.

def partition(target, predicate):
"""
split a list into two partitions with a predicate
provided.
any better ideas?
"""
true = []
false= []
for item in target:
if predicates(item):
true.append(item)
else:
false.append(item)
return true, false

but i wonder if there's another way to do this with standard libraries
or .. built-ins.
if it's not, i'd like the list objects to have partition method like
string module has.

(A) str.partition() has a /completely/ different meaning from your partition()
(B) You'd probably have better luck getting it added to the itertools
module since the concept is applicable to all iterables.
[http://docs.python.org/library/itertools.html]

Cheers,
Chris
--http://blog.rebertia.com

yep, my mistake. i shouldn't have compared it to string's partition().
i just wanted that convenience string.partition() has as a built-in.
anyway, thanks for itertools.

The way I would do it is probably apply filter to the list:[5, 7, 11, 13, 17, 19, 23]

 

[Bryan]

i know it's not very hard to get that solution.
just by implementing simple function like below.

      def partition(target, predicate):
            """
            split a list into two partitions with a predicate
provided.
            any better ideas?
            """
            true = []
            false= []
            for item in target:
                if predicates(item):
                    true.append(item)
                else:
                    false.append(item)
            return true, false

but i wonder if there's another way to do this with standard libraries
or .. built-ins.
if it's not, i'd like the list objects to have partition method

I've oft collected partitions in a dict, so I'll suggest the
generalization:

def partition(target, predicate):
result = {}
for item in target:
result.setdefault(predicate(item), []).append(item)
return result

true, false = [1,2,3,4].partition(lambda x: x >1)

print true, false
[2,3,4] [1]

With my version you'd get:
{False: [1], True: [2, 3, 4]}