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

You can create an ifelse statement that creates a vector that is equal to date.x if date.y <= date.x + 3 and date.y >= date.x and equal to date.y otherwise. Then merge the two based on this vector:

id.x <- c(1, 2, 4, 5, 7, 8, 10)
date.x <- as.Date(c("2015-01-01", "2015-01-02", "2015-01-21", "2015-01-13", "2015-01-29", "2015-01-01", "2015-01-03"),format = "%Y-%m-%d")
x <- cbind.data.frame(id.x, date.x)
id.y <- c(1, 2, 3, 6, 7, 8, 9)
date.y <- as.Date(c("2015-01-03", "2015-01-29", "2015-01-22", "2015-01-13", "2015-01-29", "2014-12-31", "2015-01-03"), format = "%Y-%m-%d")
y <- cbind.data.frame(id.y, date.y)

safe.ifelse <- function(cond, yes, no) structure(ifelse(cond, yes, no), class = class(yes))

match <- safe.ifelse(date.y <= date.x+3 & date.y >= date.x, 
            match <- date.x,
            match <- date.y)

y$date.x <- match
names(y)[1] <- "id.x"

dplyr::left_join(x, y, by=c("id.x","date.x"))

  id.x     date.x     date.y
1    1 2015-01-01 2015-01-03
2    2 2015-01-02       
3    4 2015-01-21       
4    5 2015-01-13       
5    7 2015-01-29 2015-01-29
6    8 2015-01-01       
7   10 2015-01-03       

I borrowed the safe.ifelse function from this post because the base ifelse statement results in a numeric vector rather than a date vector.