Indexing by datetime pandas dataframe fail

Question

I have the following dataframe df:

                          Candy       Apple      Banana
2016-09-14 19:00:00  109.202060  121.194138  130.372082
2016-09-14 20:00:00  109.199083  121.188817  130.380736
2016-09-14 21:00:00  109.198894  121.180553  130.366054
2016-09-14 22:00:00  109.192076  121.148722  130.307342
2016-09-14 23:00:00  109.184374  121.131068  130.276691
2016-09-15 00:00:00  109.191582  121.159304  130.316872
2016-09-15 01:00:00  109.183895  121.133062  130.269966
2016-09-15 02:00:00  109.193550  121.174708  130.337563
2016-09-15 03:00:00  109.196597  121.153076  130.274463
2016-09-15 04:00:00  109.195608  121.168936  130.276042
2016-09-15 05:00:00  109.211957  121.208946  130.330430
2016-09-15 06:00:00  109.210598  121.214454  130.365404
2016-09-15 07:00:00  109.224667  121.285534  130.508604
2016-09-15 08:00:00  109.220784  121.248828  130.389024
2016-09-15 09:00:00  109.199448  121.155439  130.212834
2016-09-15 10:00:00  109.226648  121.276439  130.427642
2016-09-15 11:00:00  109.239957  121.311719  130.462447

I want to create a second dataframe with just data from the past 6 hours.

df.index = pd.to_datetime(df.index,infer_datetime_format=True)

last_row = df.tail(1).index

six_hour = last_row - timedelta(hours=6)

df_6hr = df.loc[six_hour:last_row]
print df_6hr

I get the following error:

File "pandas/tslib.pyx", line 298, in pandas.tslib.Timestamp.new (pandas/tslib.c:9013)
File "pandas/tslib.pyx", line 1330, in pandas.tslib.convert_to_tsobject (pandas/tslib.c:25826)

TypeError: Cannot convert input to Timestamp

How come it doesn't work?

jezrael · Accepted Answer · 2016-09-30 08:45:55Z

2

You need add [0], because you need select first item of list:

last_row = df.tail(1).index[0]
print (last_row)
2016-09-15 11:00:00

last_row = df.tail(1).index
print (last_row)
DatetimeIndex(['2016-09-15 11:00:00'], dtype='datetime64[ns]', freq=None)

Better solution is simple select last value of index by [-1]:

last_row = df.index[-1]
print (last_row)
2016-09-15 11:00:00

edited Sep 30, 2016 at 8:45

answered Sep 30, 2016 at 8:42

jezrael

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2 Comments

A1122 Over a year ago

Thanks that worked... How come I have to add [0]? Isn't the output just 1 row?

jezrael Over a year ago

Glad can help you!

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