Why do I keep getting a positional argument error?

问题

Can someone please explain to me why I keep getting this error: TypeError: get_n_nouns() takes 1 positional argument but 2 were given.

I have already had a look at where my problem may be by looking at a similar question (Link) But I have adapted my code going along with the answer and yet I end up with the above error.

Here is the error in full:

Traceback (most recent call last):
  File "C:/Users/...../Downloads/Comp4.1/trialTo3.py", line 21, in <module>
    app.createPhrases()
  File "C:/Users/...../Downloads/Comp4.1/trialTo3.py", line 15, in createPhrases
    words = self.get_n_nouns(1)
TypeError: get_n_nouns() takes 1 positional argument but 2 were given

Here is the code:

import csv

class apps():
    def get_n_nouns(n):
        """
        Returns the n most common nouns
        """
        with open("setPhrases.txt") as in_file:
            reader = csv.reader(in_file)
            data = [[row[0], int(row[1])] for row in list(reader)]

        return sorted(data, key=lambda x: -x[1])[:n]

    def createPhrases(self):
        words = self.get_n_nouns(1)
        for word, count in words:
            print("{}: {}".format(word, count))


app = apps()
app.createPhrases()

Can someone please explain to me where I am going wrong? Any help is much appreciated.

回答1:

Ok so I found out where the error was. Kind of a rookie error.

This:

def get_n_nouns(n):

Needed to be written as this:

def get_n_nouns(self, n):

I had forgot to add the self part to it. That is why I kept getting that error message.

来源：https://stackoverflow.com/questions/21354777/why-do-i-keep-getting-a-positional-argument-error