nested data structures in classes

[Joel Forrest Moxley]

Greetings python-list!

The good news is that I've been having a blast with Python since early
Spring. I've had great success in both learning the language from online
/ usegroup resources and implementing it in one of my projects. However,
I can't pretend to be an expert, and I do not have a strong comp sci
background.

This is a question that I've had for a while. Usually, I'll stumble
across the answer with repeated attempts and re-searching the groups, but
I didn't have luck with this one, even in a Dietel book I picked up at the
library. I'm assuming there's an obvious answer, so maybe ya'll can save
me some time.

My Python use involves organizing nested list information. In a
simplified example, you could imagine a list of reactants and products in
a chemical reaction. Thus,

len(nested_list_of_reactants) = len(nested_list_of_products) => "number of
reactions"
where: nested_list_of_reactants[i] => "list of reactants for reaction i"
where: nested_list_of_reactants[i][j] => "reactant j of reaction i"

And so forth. Obviously, there are many attributes associated with a
specific reaction. Currently, I just pass these attribute lists (nested
and non-nested) into and out of functions. However, I'd like to be able
to create a class that would streamline this.

E.g., (this is a MATLAB structure whose qualities I'd like to emulate):
reaction(27).name = 'fawlty towers'
reaction(27).reactant(2).name = 'john cleese'

Currently, I'd have a list and a nested list to take care of this...
reaction_name[27] = 'fawlty towers' and reactants[27][2] = 'john cleese'
if this makes sense.

Any thoughts or suggestions on this type of data structuring would be
greatly appreciated. Python love, Joel

[Joel]

Does anyone have any thoughts on this?

Joel Forrest Moxley <jf******@MIT.EDU> wrote in message news:<ma**********************************@python. org>...

Greetings python-list!

The good news is that I've been having a blast with Python since early
Spring. I've had great success in both learning the language from online
/ usegroup resources and implementing it in one of my projects. However,
I can't pretend to be an expert, and I do not have a strong comp sci
background.

This is a question that I've had for a while. Usually, I'll stumble
across the answer with repeated attempts and re-searching the groups, but
I didn't have luck with this one, even in a Dietel book I picked up at the
library. I'm assuming there's an obvious answer, so maybe ya'll can save
me some time.

My Python use involves organizing nested list information. In a
simplified example, you could imagine a list of reactants and products in
a chemical reaction. Thus,

len(nested_list_of_reactants) = len(nested_list_of_products) => "number of
reactions"
where: nested_list_of_reactants[i] => "list of reactants for reaction i"
where: nested_list_of_reactants[i][j] => "reactant j of reaction i"

And so forth. Obviously, there are many attributes associated with a
specific reaction. Currently, I just pass these attribute lists (nested
and non-nested) into and out of functions. However, I'd like to be able
to create a class that would streamline this.

E.g., (this is a MATLAB structure whose qualities I'd like to emulate):
reaction(27).name = 'fawlty towers'
reaction(27).reactant(2).name = 'john cleese'

Currently, I'd have a list and a nested list to take care of this...
reaction_name[27] = 'fawlty towers' and reactants[27][2] = 'john cleese'
if this makes sense.

Any thoughts or suggestions on this type of data structuring would be
greatly appreciated. Python love, Joel

[Joel]

For posterity, here's what ended up working. Many thanks to Tom Minka
for showing me this. I understood the class stuff in principle, but I
just couldn't implement correctly.

class ReactionClass:
def __init__(self,Name='',Reactant=[],Product=[]):
self.Name = Name
self.Reactant = Reactant
self.Product = Product
def __str__(self):
# how to print the object
return self.Name+': '+str(self.Reactant)+' ->
'+str(self.Product
)

Reaction = []
# two different ways of defining a reaction
Reaction.append(ReactionClass('Kinase',['GLUC', 'ATP'],['G6P',
'ADP']))
print(Reaction[0].Name)
print(Reaction[0])
Reaction.append(ReactionClass())
Reaction[1].Name = 'and so on'
Reaction[1].Reactant = ['one', 'two']
Reaction[1].Product = 'something else'
print(Reaction[1])
print(Reaction[1].Reactant[1])

jf******@mit.edu (Joel) wrote in message news:<e3**************************@posting.google. com>...

Does anyone have any thoughts on this?

Joel Forrest Moxley <jf******@MIT.EDU> wrote in message news:<ma**********************************@python. org>...

Greetings python-list!

The good news is that I've been having a blast with Python since early
Spring. I've had great success in both learning the language from online
/ usegroup resources and implementing it in one of my projects. However,
I can't pretend to be an expert, and I do not have a strong comp sci
background.

This is a question that I've had for a while. Usually, I'll stumble
across the answer with repeated attempts and re-searching the groups, but
I didn't have luck with this one, even in a Dietel book I picked up at the
library. I'm assuming there's an obvious answer, so maybe ya'll can save
me some time.

My Python use involves organizing nested list information. In a
simplified example, you could imagine a list of reactants and products in
a chemical reaction. Thus,

len(nested_list_of_reactants) = len(nested_list_of_products) => "number of
reactions"
where: nested_list_of_reactants[i] => "list of reactants for reaction i"
where: nested_list_of_reactants[i][j] => "reactant j of reaction i"

And so forth. Obviously, there are many attributes associated with a
specific reaction. Currently, I just pass these attribute lists (nested
and non-nested) into and out of functions. However, I'd like to be able
to create a class that would streamline this.

E.g., (this is a MATLAB structure whose qualities I'd like to emulate):
reaction(27).name = 'fawlty towers'
reaction(27).reactant(2).name = 'john cleese'

Currently, I'd have a list and a nested list to take care of this...
reaction_name[27] = 'fawlty towers' and reactants[27][2] = 'john cleese'
if this makes sense.

Any thoughts or suggestions on this type of data structuring would be
greatly appreciated. Python love, Joel