Python dictreader - 如何使 CSV 列名小写？答案

【问题标题】：Python dictreader - How to make CSV column names lowercase?Python dictreader - 如何使 CSV 列名小写？
【发布时间】：2013-06-01 00:10:39
【问题描述】：

我有一个列名大写的 CSV 文件。我正在使用 csv.dictreader 读取数据，但需要小写的列名。

我在这里找到了这段代码Accessing csv header white space and case insensitive

    import csv

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 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 dInsensitive

class 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())

我的问题是当我用

运行它时

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()

我收到此错误

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

【问题讨论】：

标签： python python-2.7 csv

【解决方案1】：

您可以将文件的第一行小写，然后再将其传递给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

【讨论】：

四年后，这仍然是一种有用且易于实施的技术。

【解决方案2】：

DictReader 是一个老式的对象，所以super() 在这里根本不起作用。您需要直接访问父类中的property 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!'

【讨论】：

感谢两位的建议。我找到了解决这个问题的另一种方法，但老实说我不记得它是什么。我确实尝试了 Martijn，但它对我不起作用。
很抱歉我的解决方案不适合您；如果你让我知道你遇到了什么问题，我也许可以帮助你克服这些问题。从我的回答中可以看出，我为您测试了代码。

【解决方案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'}

【讨论】：