subtracting 2 date columns in dataframe

Question

I have the following pandas dataframe

I want to subtract date_of_birth from date_of_death to make a new column, "years_lived" to contain the years lived. I tried all 3 ways below (individually of course)

df['years_lived'] = (df['date_of_death'] - df['date_of_birth']).dt.days
df['years_lived'] = df['date_of_death'].sub(df['date_of_birth'], axis=0)
df['years_lived'] = df['date_of_death'] - df['date_of_birth']

but I got a TypeError: unsupported operand type(s) for -: 'str' and 'str'

need minimal and reproducible example code not image https://stackoverflow.com/help/minimal-reproducible-example — Panda Kim, Dec 12 '22 at 14:06

score 1 · Accepted Answer · answered Dec 12 '22 at 14:15

1

df['years_lived'] = pd.to_datetime(df['date_of_death']) - pd.to_datetime(df['date_of_birth'])

answered Dec 12 '22 at 14:15

吴慈霆

523
2
15

score 0 · Answer 2 · answered Dec 12 '22 at 14:10

0

pd.to_datetime will convert your dates into datetime and you can subtract one from the other.

https://pandas.pydata.org/docs/reference/api/pandas.to_datetime.html

answered Dec 12 '22 at 14:10

mtm1186

103
9

score 0 · Answer 3 · answered Dec 12 '22 at 14:15

You need to convert str represenation of dates to dates before subracting.

df['years_lived'] = (df['date_of_death'].astype(dt.timedelta) - df['date_of_birth'].astype(dt.timedelta)).dt.days

or

if deosn't work convert before and then subract

df['date_of_death'] = pd.to_numeric(df['date_of_death'], errors='coerce').fillna(0).astype(int)
df['date_of_birth'] =  pd.to_numeric(df['date_of_birth'], errors='coerce').fillna(0).astype(int)
df['years_lived'] = (df['date_of_death'] - df['date_of_birth']).dt.days

subtracting 2 date columns in dataframe

3 Answers3