CODEWITHSUNDEEP
pythonmaya
masamoto
masamoto

Reputation: 33

How to add Objects to Class with a loop in Python?

I have a class which looks like this.

class CharInStageList(object):
    def __init__(self, charid, charname) :
        self.charid = charid
        self.charname = charname

into this class I would like to add lists that I have.

I know how to do it the normal way

charOne = CharInStageList(1,'Tim')
charTwo = CharInStageList(2,'Struppi')

that's not a problem what I actually want to do is to add them by using a loop.

I get my data in this form

((1,'Tim'),(4,'Struppi'))

or

((1,'Tim'),(4,'Struppi'),(5,'Nami'),(6,'Luffy'))

the amount of characters I have in the scene is always different. what I imagined would be a loop like this

charlist = ((1,'Tim'),(4,'Struppi'))
for char in charlist
    objname = CharInStageList(char[0],char[1])

something like this

I want the objname to change by itself for every object I add to the class.

How can I get this effect? I can only use python 2.6.6 for this since it's the maya 2013 python

Edit:

Thx @silas-ray @chepner @theodox I looked into Dicts a bit more and that's pretty much what I need
I use a modified version of @chepner method on it.

object_dict = dict( (y, CharInStageList(x,y)) for x,y in data )

Works like a charm

My testcode looks like this

import maya.cmds as cmds
dicttest = {}

def getdata ():  
    global dicttest   
    data = ((1,'Tim'),(4,'Struppi'),(5,'Nami'),(6,'Luffy'))
    dicttest = dict( (y,(x,y)) for x,y in data )

getdata()

def printtest() :
    for char in dicttest:
        print dicttest[char]

printtest()
dicttest.clear()

I would have liked to comment in your answers with code examples but I can't get that to work there.

Upvotes: 2

Views: 8490

Answers (3)

theodox
theodox

Reputation: 12218

@chepner's answer is a great one if you can use the *args form to fill out your class instances.

If you're just asking the most efficient way to do this from a loop, remember you can have iterate over the parts of a tuple together:

data = ((1,'Tim'),(4,'Struppi'),(5,'Nami'),(6,'Luffy'))
class_data = (CharInStageList(id, name) for id, name in data)  # "for id, name" will yield two vals

You can also use map, which is very common for doing bulk data translations. A common way to do it is with a lambda so you can write it clearly:

to_char = lambda k: CharInStageList(k[0], k[1])
class_data = map(to_char, data)

If you're doing something as simple as your example, you might not want to bother with your own class. the namedtuple is a great data structure for creating tuples that are easy to work with. It also means you can use positional or named args interchangeably, just as in @chepner's *args version:

StageListChar  = namedtuple('CharInStageList', ['id', 'name'])
class_data = map(StageListChar , data)

Upvotes: 0

chepner
chepner

Reputation: 531798

Objects are not added to a class. Instead, you can create a list of objects which are all instances of the same class, using a list comprehension and taking advantage of the *args syntax:

data = ((1,'Tim'),(4,'Struppi'),(5,'Nami'),(6,'Luffy'))
object_list = [ CharInStageList(*x) for x in data ]

Perhaps you want a dictionary instead:

object_dict = dict( (y, CharInStageList(x,y)) for x,y in data )

(Note that CharInStageList is a poor name for the class, because it's not a list; it encapsulates a single character.)

If you really want CharInStateList to be a collection of characters, try something like this, which is just a thin wrapper around a dictionary:

# Your former CharInStageList
class Character(object):
    def __init__(self, charid, charname) :
        self.charid = charid
        self.charname = char name

class OnStageCharacters(object):
    def __init__(self):
        self.characters = dict()

    # Index on-stage characters using their charid
    def add(self, character):
        self.characters[character.charid] = character

on_stage = OnStageCharacters()
for id, name in data:
    on_stage.add( Character(id, name) )

Upvotes: 2

Silas Ray
Silas Ray

Reputation: 26160

You can't (at least not without hacking at locals/globals, which is generally not a good idea) change the name you are assigning to dynamically like that. You can, however, insert them in to a dictionary where the keys are your dynamically generated names.

characters = {}
for char_data in char_list:
    characters[char_data[1]] = CharInStageList(*char_data)

Though if all your character objects are storing is name and id, it might make more sense to simplify the whole thing and just create mapping dictionaries rather than objects.

character_names_by_id = dict(char_data)
character_ids_by_name = dict((name, id) for id, name in char_data)

Upvotes: 1

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