pandas: extract date and time from timestamp

Question

I have a timestamp column where the timestamp is in the following format

2016-06-16T21:35:17.098+01:00 

I want to extract date and time from it. I have done the following:

import datetime as dt  df['timestamp'] = df['timestamp'].apply(lambda x : pd.to_datetime(str(x)))  df['dates'] = df['timestamp'].dt.date 

This worked for a while. But suddenly it does not.

If I again do df['dates'] = df['timestamp'].dt.date I get the following error

Can only use .dt accessor with datetimelike values 

Luckily, I have saved the data frame with dates in the csv but I now want to create another column time in the format 23:00:00.051

EDIT

From the raw data file (15 million samples), the timestamp column looks like following (first 5 samples):

            timestamp  0           2016-06-13T00:00:00.051+01:00 1           2016-06-13T00:00:00.718+01:00 2           2016-06-13T00:00:00.985+01:00 3           2016-06-13T00:00:02.431+01:00 4           2016-06-13T00:00:02.737+01:00 

After the following command

df['timestamp'] = df['timestamp'].apply(lambda x : pd.to_datetime(str(x))) 

the timestamp column looks like with dtype as dtype: datetime64[ns]

0    2016-06-12 23:00:00.051 1    2016-06-12 23:00:00.718 2    2016-06-12 23:00:00.985 3    2016-06-12 23:00:02.431 4    2016-06-12 23:00:02.737 

Then finally

df['dates'] = df['timestamp'].dt.date  0           2016-06-12 1           2016-06-12 2           2016-06-12 3           2016-06-12 4           2016-06-12 

EDIT 2

Found the mistake. I had cleaned the data and saved the data frame in a csv file, so I don't have to do the cleaning again. When I read the csv, the timestamp dtype changes to object. Now how do I fix this?

Answer 1

Do this first:

df['time'] = pd.to_datetime(df['timestamp']) 

Before you do your extraction as usual:

df['dates'] = df['time'].dt.date 

Answer 2

If date is in string form then:

import datetime  # this line converts the string object in Timestamp object df['DateTime'] = [datetime.datetime.strptime(d, "%Y-%m-%d %H:%M") for d in df["DateTime"]]  # extracting date from timestamp df['Date'] = [datetime.datetime.date(d) for d in df['DateTime']]   # extracting time from timestamp df['Time'] = [datetime.datetime.time(d) for d in df['DateTime']]  

If the object is already in the Timestamp format then skip the first line of code.

%Y-%m-%d %H:%M this means your timestamp object must be in the form like 2016-05-16 12:35:00.