Return a vector of dates on a given day every n weeks

scheduler.R

  library(lubridate)
library(dplyr)

scheduler <- function(day = "monday", n_weeks = 2) {
  x <- data.frame(date = seq.Date(as.Date("2021-01-01"), as.Date("2050-01-01"), by = "day")) 
  x$week <- ceiling(lubridate::week(x$date) / n_weeks)
  x$day <- tolower(as.character(lubridate::wday(x$date, abbr = FALSE, label = TRUE)))
  
  suppressWarnings({
    x[x$day %in% day, ] %>% 
      dplyr::group_by(lubridate::year(date), week, day) %>% 
      dplyr::summarise(date = min(date), .groups = "drop") %>% 
      .[["date"]]
  })
}

scheduler(day = "monday", n_weeks = 2)