Comparing a list of dates to a list of intervals

karaoke.R

library(dplyr)
library(lubridate)


## when will the two friends be in the same town?
visits <- data.frame(am_in_town = c(
  ymd(20140501) %--% ymd(20140520),
  ymd(20140615) %--% ymd(20140620),
  ymd(20140701) %--% ymd(20140710),
  ymd(20141101) %--% ymd(20141112)
  )
)

## Karaoke happens on every thursday
karaoke <- data.frame(karaoketime = ymd(20140109) + ddays(seq(from = 7, to = 350, by = 7)))

## how many opportunities will they have to karaoke?

## won't work
karaoke %>%
  rowwise %>%
  mutate(karaoke_nite = any(karaoketime %within% visits[["am_in_town"]]))
  

is_in_an_interval <- function(a_date, ints = visits[["am_in_town"]]){
  any(a_date %within% ints)
}

is_in_an_interval(karaoke$karaoketime[[1]])
sapply(karaoke$karaoketime, is_in_an_interval)

## also won't work
karaoke %>%
  rowwise %>%
  mutate(karaoke_nite = is_in_an_interval(karaoketime))

## works fine
karaoke %>%
  rowwise %>%
  do(karaoke_nite = is_in_an_interval(.$karaoketime)) %>%
  ungroup

library(microbenchmark)

microbenchmark({karaoke %>%
                 rowwise %>%
                 do(karaoke_nite = is_in_an_interval(.$karaoketime)) %>%
                 ungroup},
               sapply(karaoke$karaoketime, is_in_an_interval))

## perhaps the simplest answer is to rely on sapply
karaoke %>%
  mutate(karaokenite = sapply(karaoketime, is_in_an_interval))

This is what I did to subset straight away instead of creating a true/false column:

karaoke %>% 
  filter(sapply(karaoketime, is_in_an_interval))