R: resumir respuestas de opción múltiple

coalesce.R

``` r
library(tidyverse)
library(naniar) 
# more on naniar: https://cran.r-project.org/web/packages/naniar/vignettes/replace-with-na.html

#create foo dataset
foo <- tibble(xA=c(1,rep(NA,2),2),
              xB=c(rep(NA,2),5:4),
              xC=2:5) %>% 
  mutate_all(.funs = as.double)

#execute coalesce, str_c and paste
foo %>% 
  mutate(coalesce_l = coalesce(!!! select(.,1:3)),
         coalesce_r = coalesce(!!! select(.,3:1)),
         str_c = str_c(!!! select(.,1:3),sep = ".")) %>% 
  mutate_at(.vars = vars(starts_with("x")),
            .funs = str_replace_na, "") %>% 
  mutate(paste = paste(!!! select(.,1:3),sep=".")) %>% 
  replace_with_na_at(.vars = vars(starts_with("x")), 
                     condition = ~.x %in% c("") )
#> # A tibble: 4 x 7
#>   xA    xB    xC    coalesce_l coalesce_r str_c paste
#>   <chr> <chr> <chr>      <dbl>      <dbl> <chr> <chr>
#> 1 1     <NA>  2              1          2 <NA>  1..2 
#> 2 <NA>  <NA>  3              3          3 <NA>  ..3  
#> 3 <NA>  5     4              5          4 <NA>  .5.4 
#> 4 2     4     5              2          5 2.4.5 2.4.5
```

<sup>Created on 2020-02-12 by the [reprex package](https://reprex.tidyverse.org) (v0.3.0)</sup>