Subset dataframe where date is within x days of a vector of dates in R -

i have vector of dates e.g.

dates <- c('2013-01-01', '2013-04-02', '2013-06-10', '2013-09-30') 

and dataframe contains date column e.g.

df <- data.frame(                 'date' = c('2013-01-04', '2013-01-22', '2013-10-01', '2013-10-10'),                 'a'    = c(1,2,3,4),                 'b'    = c('a', 'b', 'c', 'd')                 ) 

and would subset dataframe contains rows date less 5 days after of dates in 'dates' vector.

i.e. initial dataframe looks this

date       b  2013-01-04 1 2013-01-22 2 b 2013-10-01 3 c 2013-10-10 4 d 

after query left first , third row (since 2013-01-04 within 5 days of 2013-01-01 , 2013-10-01 within 5 days of 2013-09-30)

does know of best way this?

thanks in advance

this easy (and fast) data.table roll:

library(data.table) dt = data.table(df)  # convert date (or idate) have numbers instead of strings dates # set key dates join dt[, date := as.date(date)] dates = data.table(date = as.date(dates), key = 'date')  # join roll of 5 days, throwing out dates don't match dates[dt, roll = 5, nomatch = 0] #         date b #1: 2013-01-04 1 #2: 2013-10-01 3 c