df['established_date']=[datetime.datetime.strptime(x,'%d-%m-%y').strftime("%y-%m-%d") if not x=="nan" else x for x in df.established_date]

I am not getting why it is not working.

or

I am trying to convert 12-07-17 this date fromat to 2017-07-12 this format.

I have written above code but it isn't working.

CodePudding user response：

There's a simpler method, that's designed for this, called pd.to_datetime:

df.established_date = pd.to_datetime(df.established_date, errors='coerce').dt.strftime('%Y-%d-%m')