Why put + and %>% at the end of lines?

[alistaire]

@nick

Edit: If it’s a problem on a regular basis while you develop code, you could end your %>% chains with {.}:

delays <- flights %>%
    group_by(dest) %>%
    #summarise(distance = mean(distance)) %>%
    {.}

That last statement is basically an identity operator for pipes and will not change the output.

You can also pipe into I or identity—which similarly terminate the pipeline without changing the output—to debug:

library(dplyr)

nycflights13::flights %>%
    group_by(dest) %>%
    #summarise(distance = mean(distance)) %>%
    I
#> # A tibble: 336,776 x 19
#> # Groups:   dest [105]
#>     year month   day dep_time sched_dep_time dep_delay arr_time
#>  * <int> <int> <int>    <int>          <int>     <dbl>    <int>
#>  1  2013     1     1      517            515         2      830
#>  2  2013     1     1      533            529         4      850
#>  3  2013     1     1      542            540         2      923
#>  4  2013     1     1      544            545        -1     1004
#>  5  2013     1     1      554            600        -6      812
#>  6  2013     1     1      554            558        -4      740
#>  7  2013     1     1      555            600        -5      913
#>  8  2013     1     1      557            600        -3      709
#>  9  2013     1     1      557            600        -3      838
#> 10  2013     1     1      558            600        -2      753
#> # ... with 336,766 more rows, and 12 more variables: sched_arr_time <int>,
#> #   arr_delay <dbl>, carrier <chr>, flight <int>, tailnum <chr>,
#> #   origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
#> #   minute <dbl>, time_hour <dttm>