Question

I have this class definition, it is a datafile that will be read and a single column and sample rate information will be extracted.

class dataFile:
    def __init__(self, oldname, folName):
            self.name = oldname                 # Original File name
            self.nm_split = os.path.splitext(oldname)
            self.newName = str(self.nm_split[0] + "_trimmed" + self.nm_split[1]) 
            self.path = "./" + folName  ## Output Folder path
            self.y = []     ## Data to be extracted into list





        def readDat(self):       ## Extract the voltage column and put into array
            with open(self.name) as f:
                for line in f:
                    if line.startswith('%'):
                        if datafile.lookUp in line:
                            self.sRate = float(str.split(line)[3])
                        else:
                            continue

                    elif not len(line.strip()) ==0:
                        row = line.split()
                        self.y.append(float(row[2]))

                    else:
                        continue

            self.y = np.array(self.y);

            return self.y, self.sRate

When I run the program, and specifically the readDat() function, I get the following Message:

AttributeError: datafile instance has no attribute 'sRate'

Clearly it is defined within that first if statement in readDat so why isn't the interpreter seeing it?

Answer 1

One of the ifs before sRate is defined is not doing what you expect it to and sRate is never being declared.

I don't see a declaration for datfile.lookUp either:

            for line in f:
                if line.startswith('%'):
                    if datafile.lookUp in line: # <---- lookUp?
                        self.sRate = float(str.split(line)[3])
                    else:
                        continue

Consider declaring .sRate with a default value; it's not pythonic but it can avoid confusion.

Python Class variables not being initialized

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