Join dataframes by id and overlapping date range

Question

I have two dataframes x and y that contain columns for ids and for dates.

id.x <- c(1, 2, 4, 5, 7, 8, 10)
date.x <- as.Date(c(\"2015-01-01\", \"201         


        

Answer 1

Using inner join of y and x data tables by setting the keys to id of both datatables, and then checking for date conditions, and finally extract the true ones.

library("data.table")

x <- as.data.table(x)

y <- as.data.table(y)

setkey(x, id.x)

setkey(y, id.y)

z <- y[x, nomatch = 0][, j = .(is_true = ((date.y <= date.x + 3) & (date.y > date.x)), id.y, date.x, date.y)][i = is_true == TRUE]

> z
   is_true id.y     date.x     date.y
1:    TRUE    1 2015-01-01 2015-01-03