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Create a new Pandas column with only the year of the other column

I have the following df where 'per_end_date' is a Datetime object.

zacks_mktv_df[:4]

ticker | per_end_date | mkt_val
--------------------------------
A      | 2016-12-31   | 14648.84
A      | 2015-12-31   | 13704.02
A      | 2014-12-31   | 13751.83

I want to grab the year from each row in the "per_end_date" column and make another row out of it, so for my table above it will look like.

ticker | per_end_date | mkt_val  |
--------------------------------------------
A      | 2016-12-31   | 14648.84 | 2016
A      | 2015-12-31   | 13704.02 | 2015
A      | 2014-12-31   | 13751.83 | 2014

I've tried this.

zacks_mktv_df['per_fisc_year'] = zacks_mktv_df[zacks_mktv_df.per_end_date.dt.year]

Getting the following error:

IndexError: indices are out-of-bounds
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2 answers


you can use

zacks_mktv_df['per_fisc_year'] = zacks_mktv_df['per_end_date'].dt.year


If the column per_end_date

is, for example. datetime64

...

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I was able to achieve this with .assign as well as the following.



zacks_mktv_df.assign(per_fisc_year= zacks_mktv_df.per_end_date.dt.year)
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