使用类，方法定义变量 [英] Using Class, Methods to define variables

问题描述

我在数据库中保存了许多具有相应数据的化学物质，如何通过其公式(例如o2)返回特定化学物质及其数据.

I have a number of chemicals with corresponding data held within a database, how do I go about returning a specific chemical, and its data, via its formula, eg o2.

class SourceNotDefinedException(Exception):
def __init__(self, message):
    super(SourceNotDefinedException, self).__init__(message)

class tvorechoObject(object):
"""The class stores a pair of objects, "tv" objects, and "echo" objects. They are accessed
simply by doing .tv, or .echo. If it does not exist, it will fall back to the other variable.
If neither are present, it returns None."""
def __init__(self, echo=None, tv=None):
    self.tv = tv
    self.echo = echo

def __repr__(self):
    return str({"echo": self.echo, "tv": self.tv}) # Returns the respective strings

def __getattribute__(self, item):
    """Altered __getattribute__() function to return the alternative of .echo / .tv if the requested
    attribute is None."""

    if item in ["echo", "tv"]:    
        if object.__getattribute__(self,"echo") is None: # Echo data not present
            return object.__getattribute__(self,"tv") # Select TV data
        elif object.__getattribute__(self,"tv") is None: # TV data not present
            return object.__getattribute__(self,"echo") # Select Echo data
        else:
            return object.__getattribute__(self,item) # Return all data

    else:
        return object.__getattribute__(self,item) # Return all data


class Chemical(object):
    def __init__(self, inputLine, sourceType=None):
        self.chemicalName = TVorEchoObject()    
        self.mass = TVorEchoObject()
        self.charge = TVorEchoObject()


        self.readIn(inputLine, sourceType=sourceType)

def readIn(self, inputLine, sourceType=None):

    if sourceType.lower() == "echo": # Parsed chemical line for Echo format 


        chemicalName            = inputLine.split(":")[0].strip()
        mass               = inputLine.split(":")[1].split(";")[0].strip()
        charge                 = inputLine.split(";")[1].split("]")[0].strip()


        # Store the objects
        self.chemicalName.echo = chemicalName
        self.mass.echo = mass
        self.charge.echo = charge


    elif sourceType.lower() == "tv": # Parsed chemical line for TV format


        chemicalName          = inputLine.split(":")[0].strip()
        charge               = inputLine.split(":")[1].split(";")[0].strip()
        mass                 = inputLine.split(";")[1].split("&")[0].strip()


        # Store the objects
        self.chemicalName.tv = chemicalName
        self.charge.tv = charge
        self.mass.tv  = molecularWeight

    else:
        raise SourceNotDefinedException(sourceType + " is not a valid `sourceType`") # Otherwise print 


def toDict(self, priority="echo"):
    """Returns a dictionary of all the variables, in the form {"mass":<>, "charge":<>, ...}.
    Design used is to be passed into the Echo and TV style line format statements."""
    if priority in ["echo", "tv"]:
    # Creating the dictionary by a large, to avoid repeated text
        return dict([(attributeName, self.__getattribute__(attributeName).__getattribute__(priority))
            for attributeName in ["chemicalName", "mass", "charge"]])
    else:
        raise SourceNotDefinedException("{0} source type not recognised.".format(priority)) # Otherwise print






from ParseClasses import Chemical
allChemical = []
chemicalFiles = ("/home/temp.txt")


for fileName in chemicalFiles:
    with open(fileName) as sourceFile:
        for line in sourceFile:
        allChemical.append(Chemical(line, sourceType=sourceType))

for chemical in allChemical:
    print chemical.chemicalName #Prints all chemicals and their data in list format

for chemical in allChemical(["o2"]):
    print chemical.chemicalName

输出以下错误，但我没有运气试图纠正该错误； TypeError:列表"对象不可调用

outputs the following error which I have tried to remedy with no luck; TypeError: 'list' object is not callable

推荐答案

尝试使用此功能:

def chemByString(chemName,chemicals,priority="echo"):
    for chemical in chemicals:
        chemDict = chemical.toDict(priority)
        if chemDict["chemicalName"] == chemName
            return chemical
    return None

此函数正在使用Chemical类中的toDict()方法.您从Chemical类粘贴的代码说明，此方法从化学对象返回字典:

This function is using the toDict() method found in the Chemical class. The code you pasted from the Chemical class explains that this method returns a dictionary from the chemical object:

def toDict(self, priority="echo"):
    """Returns a dictionary of all the variables, in the form {"mass":<>, "charge":<>, ...}.
    Design used is to be passed into the Echo and TV style line format statements."""
    if priority in ["echo", "tv"]:
    # Creating the dictionary by a large, to avoid repeated text
        return dict([(attributeName, self.__getattribute__(attributeName).__getattribute__(priority))
            for attributeName in ["chemicalName", "mass", "charge"]])
    else:
        raise SourceNotDefinedException("{0} source type not recognised.".format(priority)) # Otherwise print

这本字典看起来像这样:

This dictionary looks like this:

"chemicalName" : <the chemical name>
"mass" :         <the mass>
"charge" :       <the charge>

我在上面创建的函数的作用是遍历列表中的所有化学物质，找到名称等于"o2"的第一个化学物质，然后返回该化学物质.使用方法如下:

What the function I created above does is iterate through all of the chemicals in the list, finds the first one with a name equal to "o2", and returns that chemical. Here's how to use it:

chemByString("o2",allChemicals).chemicalName

如果上述方法不起作用，则可能要尝试使用替代优先级("tv")，尽管我不确定这是否会有效果:

If the above does not work, may want to try using the alternative priority ("tv"), though I'm unsure if this will have any effect:

chemByString("o2",allChemicals,"tv").chemicalName

如果未找到该化学物，则该函数返回None:

If the chemical isn't found, the function returns None:

chemByString("myPretendChemical",allChemicals).chemicalName

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