date-interval-thing.R

``` r
library(tidyverse)
library(lubridate)
#> 
#> Attaching package: 'lubridate'
#> The following objects are masked from 'package:base':
#> 
#>     date, intersect, setdiff, union

# As an example, let's say I have a dataframe of birthdays:

birthdays <- tibble(name =   c("Anna", "Bobby", "Camille", "Deanna", "Ernie", "Francine"),
                    birthday = c("2020-05-02", "2020-03-25", "2020-06-08", "2020-01-31", "2020-08-14", "2020-07-03") %>% as_date())

# And I have another dataframe with the data ranges for various astrological "signs": 

sign <- tibble(name = c("Aries", "Taurus", "Gemini", "Cancer", "Leo"),
               start_date = c("2020-03-21", "2020-04-20", "2020-05-21", "2020-06-21", "2020-07-23") %>% as_date(),
               end_date = c("2020-04-19", "2020-05-20", "2020-06-20", "2020-07-22", "2020-08-22") %>% as_date()) %>%
  mutate(interval = interval(start_date, end_date))

# For each row of `birthdays`, I can manually calculate each sign:

birthdays %>%
  mutate(is_aries = birthday %within% sign$interval[1],
         is_taurus = birthday %within% sign$interval[2])
#> # A tibble: 6 x 4
#>   name     birthday   is_aries is_taurus
#>   <chr>    <date>     <lgl>    <lgl>    
#> 1 Anna     2020-05-02 FALSE    TRUE     
#> 2 Bobby    2020-03-25 TRUE     FALSE    
#> 3 Camille  2020-06-08 FALSE    FALSE    
#> 4 Deanna   2020-01-31 FALSE    FALSE    
#> 5 Ernie    2020-08-14 FALSE    FALSE    
#> 6 Francine 2020-07-03 FALSE    FALSE

get_sign_name <- function(date) {
  is_sign <- date %within% sign$interval
  
  if (!any(is_sign))
    return("No corresponding sign")

  sign$name[which(is_sign)]
}

birthdays %>% 
  mutate(
    sign = map_chr(birthday, get_sign_name)
  )
#> # A tibble: 6 x 3
#>   name     birthday   sign                 
#>   <chr>    <date>     <chr>                
#> 1 Anna     2020-05-02 Taurus               
#> 2 Bobby    2020-03-25 Aries                
#> 3 Camille  2020-06-08 Gemini               
#> 4 Deanna   2020-01-31 No corresponding sign
#> 5 Ernie    2020-08-14 Leo                  
#> 6 Francine 2020-07-03 Cancer
```

<sup>Created on 2021-02-03 by the [reprex package](https://reprex.tidyverse.org) (v1.0.0.9000)</sup>