问题描述
我目前正在使用 SciPy.integrate.ode.我需要能够轻松地向系统添加物种和反应，因此我必须编写一些非常通用的代码.我的方案如下所示:
I'm currently implementing a complex microbial food-web in Python using SciPy.integrate.ode. I need the ability to easily add species and reactions to the system, so I have to code up something quite general. My scheme looks something like this:
class Reaction(object):
def __init__(self):
#stuff common to all reactions
def __getReactionRate(self, **kwargs):
raise NotImplementedError
... Reaction subclasses that
... implement specific types of reactions
class Species(object):
def __init__(self, reactionsDict):
self.reactionsDict = reactionsDict
#reactionsDict looks like {'ReactionName':reactionObject, ...}
#stuff common to all species
def sumOverAllReactionsForThisSpecies(self, **kwargs):
#loop over all the reactions and return the
#cumulative change in the concentrations of all solutes
...Species subclasses where for each species
... are defined and passed to the superclass constructor
class FermentationChamber(object):
def __init__(self, speciesList, timeToSolve, *args):
#do initialization
def step(self):
#loop over each species, which in turn loops
#over each reaction inside it and return a
#cumulative dictionary of total change for each
#solute in the whole system
if __name__==__main__:
f = FermentationChamber(...)
o = ode(...) #initialize ode solver
while o.successful() and o.t<timeToSolve:
o.integrate()
#process o.t and o.y (o.t contains the time points
#and o.y contains the solution matrix)
所以，问题是，当我遍历 Species.sumOverAllReactionsForThisSpecies() 和 FermentationChamber.step() 中的字典时，是否保证字典的迭代顺序如果在第一次和最后一次迭代之间没有从字典中添加或删除元素，是否相同?也就是说，我可以假设在每次迭代时从字典中创建的 numpy 数组的顺序不会改变吗?例如，如果字典的格式为 {'Glucose':10, 'Fructose':12}，如果从该字典创建的 Array 将总是具有相同的顺序(不管是什么这个顺序是，只要它是确定性的.
So, the question is, when I iterate over the dictionaries in Species.sumOverAllReactionsForThisSpecies() and FermentationChamber.step(), is the iteration order of the dictionaries guaranteed to be the same if no elements are added or removed from the dictionaries between the first and the last iteration? That is, can I assume that the order of the numpy array created at each iteration from the dictionary will not vary? For example, if a dictionary has the format {'Glucose':10, 'Fructose':12}, if an Array created from this dictionary will always have the same order (it doesn't matter what that order is, as long as it's deterministic).
抱歉发了这么大的帖子，我只是想让你知道我来自哪里.
Sorry for the mega-post, I just wanted to let you know where I'm coming from.
推荐答案
Python 3.1 有一个 collections.OrderedDict 类可用于此目的.它也非常高效:所有方法的 Big-O 运行时间与常规字典相同."
Python 3.1 has a collections.OrderedDict class that can be used for this purpose. It's very efficient, too: "Big-O running times for all methods are the same as for regular dictionaries."
OrderedDict 的代码本身与 Python 2.x 兼容，尽管一些继承的方法(来自 _abcoll 模块)确实使用了仅 Python 3 的功能.但是，它们可以轻松修改为 2.x 代码.
The code for OrderedDict itself is compatible with Python 2.x, though some inherited methods (from the _abcoll module) do use Python 3-only features. However, they can be modified to 2.x code with minimal effort.
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