datetime to string with series in pandas

Question

How should I transform from datetime to string? My attempt:

dates = p.to_datetime(p.Series(['20010101', '20010331']), format = '%Y%m%d')
dates.str

score 165 · Accepted Answer · edited Feb 25 '22 at 03:50

165

There is no .str accessor for datetimes and you can't do .astype(str) either.

Instead, use .dt.strftime:

>>> series = pd.Series(['20010101', '20010331'])
>>> dates = pd.to_datetime(series, format='%Y%m%d')
>>> dates.dt.strftime('%Y-%m-%d')
0    2001-01-01
1    2001-03-31
dtype: object

See the docs on customizing date string formats here: strftime() and strptime() Behavior.

For old pandas versions <0.17.0, one can instead can call .apply with the Python standard library's datetime.strftime:

>>> dates.apply(lambda x: x.strftime('%Y-%m-%d'))
0    2001-01-01
1    2001-03-31
dtype: object

edited Feb 25 '22 at 03:50

Mateen Ulhaq

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answered May 08 '15 at 20:25

EdChum

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Thanks @EdChum. But now I found another problem. If a have NaT.? How to solve it ? `dates = p.to_datetime(p.Series(['20010101', '20010331',None]), format = '%Y%m%d') dates.apply(lambda x: x.strftime('%Y-%m-%d'))` – Diego May 08 '15 at 21:39
1

Drop them first is one option so `dates.dropna().apply(lambda x: x.strftime('%Y-%m-%d'))` – EdChum May 08 '15 at 21:40
@EdChum This still doesn't turn dates into strings. `type(dates.df.strftime(...))` says ``. You need to add `.tolist()`. pandas version 0.25.3 – horaceT Oct 20 '20 at 18:52

score 50 · Answer 2 · edited Feb 25 '22 at 03:33

50

As of pandas version 0.17.0, you can format with the dt accessor:

dates.dt.strftime('%Y-%m-%d')

edited Feb 25 '22 at 03:33

Mateen Ulhaq

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answered Nov 28 '15 at 03:34

Kamil Sindi

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1

this sped up my code 10 fold compared to using `datetime.strftime` inside a lambda function in a dataframe `.apply()` method (as suggested by @EdChum) – Tanguy Oct 23 '19 at 08:20

score 3 · Answer 3 · edited Jan 28 '17 at 04:42

There is a pandas function that can be applied to DateTime index in pandas data frame.

date = dataframe.index #date is the datetime index
date = dates.strftime('%Y-%m-%d') #this will return you a numpy array, element is string.
dstr = date.tolist() #this will make you numpy array into a list

the element inside the list:

u'1910-11-02'

You might need to replace the 'u'.

There might be some additional arguments that I should put into the previous functions.

datetime to string with series in pandas

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