遍历Pandas中的DateTimeIndex

import pandas as pd
import datetime

## Importing the data from the Sep 2016-August 2018
## Step count & Date features only

features = ['Date','Step count']
data = pd.read_csv('fit_daily_sum_Sep2016_Aug2018.csv', sep=',', usecols=features).set_index('Date')
# To convert data index to datetime
data.index = pd.to_datetime(data.index)

tmp = data.head()
print tmp.index
print 'first key',tmp.index[0]
print type(tmp.index[0])

fkey = pd.Timestamp(2016,9,2)
print 'fkey is',fkey
for x in xrange(0, len(tmp)):
    print 'running',fkey+datetime.timedelta(days=x)
    print tmp[fkey+datetime.timedelta(days=x)]

最后一行的第一次迭代抛出一个KeyError。控制台显示如下(浓缩)

DatetimeIndex(['2016-09-02', '2016-09-03', '2016-09-04', '2016-09-05',
           '2016-09-06'],
          dtype='datetime64[ns]', name=u'Date', freq=None)
first key 2016-09-02 00:00:00
<class 'pandas._libs.tslibs.timestamps.Timestamp'>
fkey is 2016-09-02 00:00:00
running 2016-09-02 00:00:00
KeyError: Timestamp('2016-09-02 00:00:00')

在我看来,我正在输入我知道存在的精确的密钥,但却抛出了一个密钥错误!我不确定问题出在哪里。任何帮助都将不胜感激。