SettingWithCopyWarning message when transforming Datetime Date into String Python Dataframe

Question

I am receiving the following warning message when performing the following transformation of a date into a string:

SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

I am doing the following:

Data['Date'] = Data['Date'].dt.strftime('%Y-%m-%d')

It actually suggests you to Try using .loc[row_indexer,col_indexer] = value instead — Vitalii Strimbanu
– Vitalii Strimbanu, Commented Jan 24, 2017 at 19:53
@VitaliiStrimbanu, thanks but I tried Data.loc['Date'] = Data['Date'].dt.strftime('%Y-%m-%d')it is not working and I receive the following error message: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame — MCM
– MCM, Commented Jan 24, 2017 at 19:57
You're going to have to use .apply and a lambda function out on your dataframe ala: stackoverflow.com/questions/19738169/… — Chuck
– Chuck, Commented Jan 24, 2017 at 20:04
Try Data.loc[:, 'Date'] = Data['Date'].dt.strftime('%Y-%m-%d'). See more info in this post — Parfait
– Parfait, Commented Jan 24, 2017 at 20:04

Community · Accepted Answer · 2017-05-23 12:25:57Z

2

If you provide a sample of your code, I can amend this answer to be more specific to your requirements. If this answer is deemed superfluous to the answer given in the quoted question, let me know, and I'll delete it.

I should make it clear, the following is a near exact replication of the answer to this question here: datetime to string with series in python pandas.

For some data frame:

df = pandas.Series(['20010101', '20010331'])

0    20010101
1    20010331
dtype: object

# Convert to the format you need:

dates = pandas.to_datetime(A, format = '%Y-%m-%d')

0   2001-01-01
1   2001-03-31
dtype: datetime64[ns]

# Then to convert back, do:

df2 = dates.apply(lambda x: x.strftime('%Y-%m-%d'))

0    2001-01-01
1    2001-03-31
dtype: object

edited May 23, 2017 at 12:25

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answered Jan 24, 2017 at 20:16

Chuck

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2 Comments

MCM Over a year ago

Thanks. The answers above helped. You can delete it if you want but it also helps for other problems.

Chuck Over a year ago

Ok glad it helped, I'll leave it up. But @EdChum should know: this is down to you, I make no contention.

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