Convert Pandas DF column from UTC to US-Eastern time without date

问题

I have this Pandas dataframe column:

                     time_UTC
0   2015-01-05 16:44:34+00:00
1   2015-08-11 16:44:38+00:00
2   2015-08-02 16:53:25+00:00
3   2015-08-17 16:53:25+00:00
4   2015-09-28 16:53:26+00:00
Name: time_UTC, dtype: datetime64[ns, UTC]

and I converted it from UTC to US-Eastern timezone using:

list_temp = []
    for row in df['time_UTC']:
        list_temp.append(Timestamp(row, tz = 'UTC').tz_convert('US/Eastern'))
    df['time_EST'] = list_temp

to get this:

0   2015-01-05 11:44:34-05:00
1   2015-08-11 11:44:38-05:00
2   2015-08-02 11:53:25-05:00
3   2015-08-17 11:53:25-05:00
4   2015-09-28 11:53:26-05:00
Name: time_EST, dtype: datetime64[ns, US/Eastern]

Now, I need to drop the date part of the entries so that I only get the time. Here is what I need:

0   11:44:34-05:00
1   11:44:38-05:00
2   11:53:25-05:00
3   11:53:25-05:00
4   11:53:26-05:00
Name: time_EST, dtype: datetime64[ns, US/Eastern]

Attempt:

I tried this:

print df['time_EST'].apply(lambda x: dt.time(x.hour,x.minute,x.second))

The conversion is made so that date is dropped and I only get time. But it is reverting back to the UTC timezone. Here is the output of the above command:

0    16:44:34
1    16:44:38
2    16:53:25
3    16:53:25
4    16:53:26
Name: time_EST, dtype: object

Question:

Is there a way to drop the date and keep time as US-Eastern, without automatically reverting back to UTC?

EDIT:

To recreate the problem, just copy the first DataFrame above and use this code:

import pandas as pd
from pandas.lib import Timestamp
import datetime as dt
df = pd.read_clipboard()

Then copy the remaining lines of code from the question. Any assistance with this problem would be greatly appreciated.

回答1:

You want to use strftime to format your string, also note the vectorized date manipulations:

df = pd.read_clipboard()
df.time_UTC = pd.to_datetime(df.time_UTC)
df['EST'] = (df.time_UTC.dt.tz_localize('UTC')
                        .tz_convert('US/Eastern')
                        .strftime("%H:%M:%S"))

In [41]: df
Out[41]:
                               time_UTC       EST
time_UTC
2016-02-15 16:44:34 2016-02-15 16:44:34  11:44:34
2016-02-15 16:44:38 2016-02-15 16:44:38  11:44:38
2016-02-15 16:53:25 2016-02-15 16:53:25  11:53:25
2016-02-15 16:53:25 2016-02-15 16:53:25  11:53:25
2016-02-15 16:53:26 2016-02-15 16:53:26  11:53:26

来源：https://stackoverflow.com/questions/35398944/convert-pandas-df-column-from-utc-to-us-eastern-time-without-date

标签

python-2.7

pandas

timezone