Convert year and day of year into pandas timestamp

Question

Is there a way to convert a string containing year and day of year into pandas timestamp?

eg

a_str = '2000120'  # year 2000, day 120

I tried:

pd.Timestamp(year=a_str[:4], dayofyear=a_str[4:])

but I get this error

*** TypeError: __new__() got an unexpected keyword argument 'dayofyear'

How to fix this?

Answer 1

You can use %j which is the day of the year:

In [11]: dt.datetime.strptime("2000120", "%Y%j")
Out[11]: datetime.datetime(2000, 4, 29, 0, 0)

In [12]: pd.to_datetime("2000120", format="%Y%j")
Out[12]: Timestamp('2000-04-29 00:00:00')

Note: Whilst the docs say:

Day of the year as a zero-padded decimal number.

This doesn't apear to be the case (it works even if it's not zero padded):

In [13]: dt.datetime.strptime("200020", "%Y%j")
Out[13]: datetime.datetime(2000, 1, 20, 0, 0)

In [14]: pd.to_datetime("200020", format="%Y%j")
Out[14]: Timestamp('2000-01-20 00:00:00')

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I don't think you can use the Timestamp constructor here, you have to use the to_datetime method (which allows you to pass format ).