Question

我有一个应该能够从.csv文件中读取数据的类。在类的__init__中，我读取文件并将其作为self.csv_table本地存储在类中。问题是，当我尝试在另一个函数中访问此变量时，我得到ValueError: I/O operation on closed file。如何避免此错误而是打印文件？

import csv


class CsvFile(object):
    """
    A class that allows the user to read data from a csv file. Can read columns, rows, specific fields
    """
    def __init__(self, file, delimiter="'", quotechar='"'):
        """
        file: A string. The full path to the file and the file. /home/user/Documents/table.csv
        delimter & quotechar: Strings that define how the table's rows and columns are constructed
        return: the file in a way use-able to other functions
        Initializes the csv file
        """
        with open(file, 'r') as csv_file:
            self.csv_table = csv.reader(csv_file, delimiter=delimiter, quotechar=quotechar)  # local copy of csv file

    def read_csv(self):
        """
        Prints the csv file in a simple manner. Not much can be done with this.
        """
        for row in self.csv_table:
            print(', '.join(row))

my_file = CsvFile(file)
my_file.read_csv()  # this one causes an I/O error

Answer 1

这里，您的问题是self.csv_table包含文件引用本身，而不是文件内容。一旦您退出“with”语句，文件就会关闭，您将无法再访问它。

由于您关心内容，您需要通过迭代csv_reader将内容存储在csv_table中，例如在__init__函数中，您可以执行以下操作：

def __init__(self, file, delimiter="'", quotechar='"'):
    """
    file: A string. The full path to the file and the file. /home/user/Documents/table.csv
    delimter & quotechar: Strings that define how the table's rows and columns are constructed
    return: the file in a way use-able to other functions
    Initializes the csv file
    """
    self.csv_table = []
    with open(file, 'r') as csv_file:
        csv_reader = csv.reader(csv_file, delimiter=delimiter, quotechar=quotechar)  # local copy of csv file
        for data_entry in csv_reader:
            self.csv_table.append(data_entry)

然后，您将能够以self.csv_table的形式访问列表列表。

或者，如果你真的关心这个文件，你需要重新打开它，任何时候你想要访问它=＆gt; 通过self.csv_filename更改self.csv_table，并在read_csv函数中，只需重新打开文件并随时创建阅读器=＆gt;

import csv


class CsvFile(object):
    """
    A class that allows the user to read data from a csv file. Can read columns, rows, specific fields
    """
    def __init__(self, filename, delimiter="'", quotechar='"'):
        """
        filename: A string. The full path to the file and the file. /home/user/Documents/table.csv
        delimter & quotechar: Strings that define how the table's rows and columns are constructed
        return: the file in a way use-able to other functions
        Initializes the csv file
        """
        self.filename = filename
        self.delimiter = delimiter
        self.quotechar = quotechar

    def read_csv(self):
        """
        Prints the csv file in a simple manner. Not much can be done with this.
        """
        with open(self.filename, 'r') as csv_file:
            csv_table = csv.reader(csv_file, delimiter=self.delimiter, quotechar=self.quotechar)  
            for row in csv_table:
                print(', '.join(row))

my_file = CsvFile(file)
my_file.read_csv()  # this one causes an I/O error

如何将文件本地存储到类？

1 个答案: