r - Abstracting the year from a date column in a dataframe -

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• extract month , year zoo::yearmon object 6 answers

i have dataframe date column

date 2008-01-01 2008-01-02 2008-01-03 2008-01-04 

how can create new column contains year these dates?

if convert data frame data table

df <- data.table(date = as.date(c('2008-01-01',                                    '2008-01-02',                                   '2008-01-03',                                   '2008-01-04'))) 

you can use nice assignment , use stringr package year

library(stringr) df[,year := str_match(date, '[0-9]{4}')[,1]]