Create month start and end dates for a date range you pass in

month_start_end.R

add_months <-  function(date, n){
  seq(date, by = paste (n, "months"), length = 2)[2]
}

make_date_ranges <- function(start, end){
  
  starts <- seq(from = start,
                to =  Sys.Date()-1 ,
                by = "1 month")
  
  ends <- c((seq(from = add_months(start, 1),
                 to = end,
                 by = "1 month" ))-1,
            (Sys.Date()-1))
  
  data.frame(starts,ends)
  
}

## useage
make_date_ranges(as.Date("2017-01-01"), Sys.Date())