Question

我刚刚参加了Udacity的数据分析课程。我的代码是：

enrollments_filename= '/Users/abc/Desktop/Udacity - Intro to Data Analysis/enrollments.csv'

def open_file(filename):
    with open(filename, 'rb') as f:
        reader = unicodecsv.DictReader(f)
        return list(reader)

enrollments = open_file(enrollments_filename)

# Takes a date as a string, and returns a Python datetime object. 
# If there is no date given, returns None

from datetime import datetime as dt    
def parse_date(date):
    if date == '':
        return None
    else:
        return dt.strptime(date, '%Y-%m-%d')

# Takes a string which is either an empty string or represents an integer,
# and returns an int or None.

def parse_maybe_int(i):
    if i == '':
        return None
    else:
        return int(i)

for enrollment in enrollments:
    enrollment['cancel_date'] = parse_date(enrollment['cancel_date'])
    enrollment['days_to_cancel'] = parse_maybe_int(enrollment['days_to_cancel'])
    enrollment['is_canceled'] = enrollment['is_canceled'] == 'True'
    enrollment['is_udacity'] = enrollment['is_udacity'] == 'True'
    enrollment['join_date'] = parse_date(enrollment['join_date'])

enrollments[0]

这是我得到的错误：

TypeError: strptime() argument 1 must be string, not datetime.datetime

任何人都可以向我解释原因吗？当我将date更改为str(date)时，这是我得到的错误：

//anaconda/lib/python2.7/_strptime.pyc in _strptime(data_string, format)
    333     if len(data_string) != found.end():
    334         raise ValueError("unconverted data remains: %s" %
--> 335                           data_string[found.end():])
    336 
    337     year = None


ValueError: unconverted data remains:  00:00:00

奇怪的是，当我第一次运行代码时，它可以工作。但后来我第二次重新按下并返回错误！非常感谢！

Answer 1

我打赌你在shell / session中两次运行这行：

enrollment['cancel_date'] = parse_date(enrollment['cancel_date'])

第一次有效，但现在注册[＆＃39; cancel_date＆＃39;]是日期，而不是字符串。第二次运行它 - 错误。

参数1必须是字符串，而不是datetime.datetime？

1 个答案: