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Data Tree urgent help!!!!!!

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  Data Tree urgent help!!!!!! anadionisio257@gmail.com - 2013-02-19 04:14 -0800
    Re: Data Tree urgent help!!!!!! Peter Otten <__peter__@web.de> - 2013-02-19 13:34 +0100
      Re: Data Tree urgent help!!!!!! Ana Dionísio <anadionisio257@gmail.com> - 2013-02-19 04:50 -0800
      Re: Data Tree urgent help!!!!!! Ana Dionísio <anadionisio257@gmail.com> - 2013-02-19 04:50 -0800
      Re: Data Tree urgent help!!!!!! Leo Breebaart <leo@lspace.org> - 2013-02-20 10:18 +0000
        Re: Data Tree urgent help!!!!!! Peter Otten <__peter__@web.de> - 2013-02-20 11:46 +0100
        Re: Data Tree urgent help!!!!!! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-20 22:01 +1100
          Re: Data Tree urgent help!!!!!! Chris Angelico <rosuav@gmail.com> - 2013-02-20 22:16 +1100
            Re: Data Tree urgent help!!!!!! Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-20 22:47 +1100

#39211 — Data Tree urgent help!!!!!!

Hello! 
I have this lists with information and I need to make a "tree" by associating the information inside the lists. For example:

l1 = [apple, pear]
l2 = [dog, cat]
l3 = [fork, spoon]

And I need to make something like this:

l4 = [apple, dog, fork]
l5 = [apple, dog, spoon]
l6= [apple, cat, fork]
l7 = [apple, cat, spoon]
l8 = [pear, dog, fork]
etc...

How can I do this? I could use "for" cycles and "if...else" but with larger lists it gets complicated   

Is there some simple solution that I can use?

I hope you could help me  

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#39212

anadionisio257@gmail.com wrote:

> Hello!
> I have this lists with information and I need to make a "tree" by
> associating the information inside the lists. For example:
> 
> l1 = [apple, pear]
> l2 = [dog, cat]
> l3 = [fork, spoon]
> 
> And I need to make something like this:
> 
> l4 = [apple, dog, fork]
> l5 = [apple, dog, spoon]
> l6= [apple, cat, fork]
> l7 = [apple, cat, spoon]
> l8 = [pear, dog, fork]
> etc...
> 
> How can I do this? I could use "for" cycles and "if...else" but with
> larger lists it gets complicated
> 
> Is there some simple solution that I can use?

Try itertools.product():

>>> class Name(str):
...     def __repr__(self):
...             return self
... 
>>> apple, pear, dog, cat, fork, spoon = map(Name, "apple pear dog cat fork 
spoon".split())
>>> fruit = [apple, pear]
>>> pets = [dog, cat]
>>> cutlery = [fork, spoon]
>>> from itertools import product
>>> for item in product(fruit, pets, cutlery):
...     print item
... 
(apple, dog, fork)
(apple, dog, spoon)
(apple, cat, fork)
(apple, cat, spoon)
(pear, dog, fork)
(pear, dog, spoon)
(pear, cat, fork)
(pear, cat, spoon)

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#39214

Thank you so much!!!!!!! It works perfectly!!!

;)

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#39215

Thank you so much!!!!!!! It works perfectly!!!

;)

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#39334

Peter Otten <__peter__@web.de> writes:

> >>> class Name(str):
> ...     def __repr__(self):
> ...             return self
> ... 
> >>> apple, pear, dog, cat, fork, spoon = map(Name, "apple pear dog cat fork spoon".split())

Is there any reason why you introduced the Name class? In Python
2.7 this works equally well if I just do:

>>> apple, pear, dog, cat, fork, spoon = map(str, "apple pear dog cat fork spoon".split())

So I was wondering why you used Name.

-- 
Leo Breebaart  <leo@lspace.org>

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#39338

Leo Breebaart wrote:

> Peter Otten <__peter__@web.de> writes:
> 
>> >>> class Name(str):
>> ...     def __repr__(self):
>> ...             return self
>> ...
>> >>> apple, pear, dog, cat, fork, spoon = map(Name, "apple pear dog cat
>> >>> fork spoon".split())
> 
> Is there any reason why you introduced the Name class? In Python
> 2.7 this works equally well if I just do:
> 
>>>> apple, pear, dog, cat, fork, spoon = map(str, "apple pear dog cat fork
>>>> spoon".split())
> 
> So I was wondering why you used Name.

It was more for fun than profit ;) The OP gave  

[apple, dog, fork]

in his examples, and the "normal" no-nonsense approach using a list of 
strings would produce

['apple', 'dog', 'fork']

I was tempted to carry this even further with

>>> class Name(str):
...     def __repr__(self): return self
... 
>>> class Namespace(dict):
...     def __missing__(self, key):
...             self[key] = result = Name(key)
...             return result
... 
>>> fruit, pets, cutlery = eval("[apple, pear], [dog, cat], [fork, spoon]", 
Namespace())
>>> fruit
[apple, pear]

but resisted until now...

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#39342

Leo Breebaart wrote:

> Peter Otten <__peter__@web.de> writes:
> 
>> >>> class Name(str):
>> ...     def __repr__(self):
>> ...             return self
>> ...
>> >>> apple, pear, dog, cat, fork, spoon = map(Name, "apple pear dog cat
>> >>> fork spoon".split())
> 
> Is there any reason why you introduced the Name class? In Python
> 2.7 this works equally well if I just do:
> 
>>>> apple, pear, dog, cat, fork, spoon = map(str, "apple pear dog cat fork
>>>> spoon".split())
> 
> So I was wondering why you used Name.

I'm wondering why you used map.


apple, pear, dog, cat, fork, spoon = "apple pear dog cat fork spoon".split()


:-)


-- 
Steven

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#39346

On Wed, Feb 20, 2013 at 10:01 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> Leo Breebaart wrote:
>
>> Peter Otten <__peter__@web.de> writes:
>>
>>> >>> class Name(str):
>>> ...     def __repr__(self):
>>> ...             return self
>>> ...
>>> >>> apple, pear, dog, cat, fork, spoon = map(Name, "apple pear dog cat
>>> >>> fork spoon".split())
>>
>> Is there any reason why you introduced the Name class? In Python
>> 2.7 this works equally well if I just do:
>>
>>>>> apple, pear, dog, cat, fork, spoon = map(str, "apple pear dog cat fork
>>>>> spoon".split())
>>
>> So I was wondering why you used Name.
>
> I'm wondering why you used map.
>
>
> apple, pear, dog, cat, fork, spoon = "apple pear dog cat fork spoon".split()

Why, in case someone monkeypatched split() to return something other
than strings, of course!

Sorry, I've been learning Ruby this week, and I fear it may be
damaging to my mind...

ChrisA

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#39352

Chris Angelico wrote:

>> I'm wondering why you used map.
>>
>>
>> apple, pear, dog, cat, fork, spoon = "apple pear dog cat fork
>> spoon".split()
> 
> Why, in case someone monkeypatched split() to return something other
> than strings, of course!
> 
> Sorry, I've been learning Ruby this week, and I fear it may be
> damaging to my mind...

:-)


You cannot monkey-patch builtins themselves in Python. Since the string is a
literal, it is guaranteed to be a builtin string, and the split method is
guaranteed to be the builtin str.split method.

This is, however, not true in the earlier example of map(str, ...) since
either of map or str could be shadowed by a global function of the same
name, or even monkey-patched across the whole Python environment:

py> import __builtin__  # Python 2.7
py> __builtin__.str = lambda x: len(x)
py> __builtin__.map = lambda func, items: [10000+func(x) for x in items]
py> map(str, "apple, pear, dog".split())
[10006, 10005, 10003]


So unlike Ruby, Python restricts what you can monkey-patch, and discourages
you from doing it even when you can. Oh, and I can reverse my monkey-patch
easily:

py> reload(__builtin__)
<module '__builtin__' (built-in)>
py> map(str, "apple, pear, dog".split())
['apple,', 'pear,', 'dog']



-- 
Steven

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