Python dictreader-如何使CSV列名变为小写？

Question

我有一个CSV文件，其列名均为大写。我正在使用csv.dictreader读取数据，但需要使用小写字母的列名称。我在这里找到此代码访问csv标头空白且不区分大小写    import csvclass DictReaderInsensitive(csv.DictReader):    # This class overrides the csv.fieldnames property.    # All fieldnames are without white space and in lower case    @property    def fieldnames(self):        return [field.strip().lower() for field in super(DictReaderInsensitive, self).fieldnames]    def __next__(self):        # get the result from the original __next__, but store it in DictInsensitive        dInsensitive = DictInsensitive()        dOriginal = super(DictReaderInsensitive, self).__next__()        # store all pairs from the old dict in the new, custom one        for key, value in dOriginal.items():            dInsensitive[key] = value        return dInsensitiveclass DictInsensitive(dict):    # This class overrides the __getitem__ method to automatically strip() and lower() the input key    def __getitem__(self, key):        return dict.__getitem__(self, key.strip().lower())我的问题是当我使用datafile = open(self.ifs_data_file,'rU')        csvDict = DictReaderInsensitive(datafile)        for row in csvDict:            print row            #self.db.ifs_data.insert(**row)            #self.db.commit()我得到这个错误Traceback (most recent call last):  File "D:\Development\python\supplier_review\supplier_review.py", line 239, in update_ifs_data    for row in csvDict:  File "D:\Python27_5\lib\csv.py", line 103, in next    self.fieldnames  File "D:\Development\python\supplier_review\supplier_review.py", line 288, in fieldnames    return [field.strip().lower() for field in super(DictReaderInsensitive, self).fieldnames]TypeError: must be type, not classobj

Answer 1

您可以将文件的第一行小写，然后再传递给DictReader：

import csv

import itertools

def lower_first(iterator):

    return itertools.chain([next(iterator).lower()], iterator)

with open(ifs_data_file, 'rU') as datafile:

    csvDict = csv.DictReader(lower_first(datafile))

    for row in csvDict:

        print row    

Answer 2

DictReader是一个老式的对象，因此super()在这里根本无法使用。您需要直接访问property父类中的对象。在Python 2中，您要覆盖.next()方法，而不是.__next__()：

class DictReaderInsensitive(csv.DictReader):

    # This class overrides the csv.fieldnames property.

    # All fieldnames are without white space and in lower case

    @property

    def fieldnames(self):

        return [field.strip().lower() for field in csv.DictReader.fieldnames.fget(self)]

    def next(self):

        return DictInsensitive(csv.DictReader.next(self))

演示：

>>> example = '''\

... foo,Bar,BAZ

... 42,3.14159,Hello world!'''.splitlines()

>>> csvDict = DictReaderInsensitive(example)

>>> row = next(csvDict)

>>> print row

{'bar': '3.14159', 'foo': '42', 'baz': 'Hello world!'}

>>> row['BAZ']

'Hello world!'

Answer 3

对于更简单的方法，您可以在访问字典之前简单地更新DictReader.fieldnames属性，如下所示：

>>> f = open('example-x-y-time.csv', 'rb')

>>> reader = csv.DictReader(f)

>>> reader.fieldnames

['Latitude', 'Longitude', 'Date']

>>> print next(reader)

{'Latitude': '44.8982391', 'Date': '2004-07-12', 'Longitude': '-117.7791061'}

>>> reader.fieldnames = [name.lower() for name in reader.fieldnames]

>>> print next(reader)

{'latitude': '44.6637001', 'date': '1964-04-03', 'longitude': '-123.5997009'}