为什么as_tibble（）round浮动到最接近的整数？

Question

When using as_tibble in dplyr 0.7.4 and R 3.4.1 I get the following outputs

mtcars %>% aggregate(disp ~ cyl, data=., mean) %>% as_tibble()

which outputs

# A tibble: 3 x 2
    cyl  disp
  <dbl> <dbl>
1  4.00   105
2  6.00   183
3  8.00   353

while

mtcars %>% aggregate(disp ~ cyl, data=., mean)

outputs

  cyl     disp
1   4 105.1364
2   6 183.3143
3   8 353.1000

Not really surprisingly, the following

mtcars %>% group_by(cyl) %>% summarise(disp=mean(disp))

gives again

# A tibble: 3 x 2
    cyl  disp
  <dbl> <dbl>
1  4.00   105
2  6.00   183
3  8.00   353

Why is this rounding happening and how can I avoid it?

Answer 1

This is not a rounding, it's only a way for {tibble} to display data in a pretty way:

> mtcars %>% 
+   aggregate(disp ~ cyl, data=., mean) %>% 
+   as_tibble() %>% 
+   pull(disp)
[1] 105.1364 183.3143 353.1000

If you want to see more digits, you have to print a data.frame:

> mtcars %>% 
+   aggregate(disp ~ cyl, data=., mean) %>% 
+   as_tibble() %>% 
+   as.data.frame()
  cyl     disp
1   4 105.1364
2   6 183.3143
3   8 353.1000

(and yes, the two last lines are useless)