Provide arguments to nest() and unnest() to get rid of warnings (#825)

model-many.Rmd

@@ -351,7 +351,7 @@ You can also use it on an ungrouped data frame, specifying which columns you wan
 
 ```{r}
 gapminder %>% 
-  nest(year:gdpPercap)
+  nest(data = c(year:gdpPercap))
 ```
 
 ### From vectorised functions
@@ -374,7 +374,7 @@ df %>%
 ```{r}
 df %>% 
   mutate(x2 = stringr::str_split(x1, ",")) %>% 
-  unnest()
+  unnest(x2)
 ```
 
 (If you find yourself using this pattern a lot, make sure to check out `tidyr::separate_rows()` which is a wrapper around this common pattern).
@@ -420,7 +420,7 @@ probs <- c(0.01, 0.25, 0.5, 0.75, 0.99)
 mtcars %>% 
   group_by(cyl) %>% 
   summarise(p = list(probs), q = list(quantile(mpg, probs))) %>% 
-  unnest()
+  unnest(c(p, q))
 ```
 
 ### From a named list
@@ -464,7 +464,7 @@ df %>%
     mtcars %>% 
       group_by(cyl) %>% 
       summarise(q = list(quantile(mpg))) %>% 
-      unnest()
+      unnest(q)
     ```
 
 1.  What does this code do? Why might might it be useful?
@@ -540,7 +540,7 @@ df1 <- tribble(
    2, "c",           3
 )
 df1
-df1 %>% unnest(y, z)
+df1 %>% unnest(c(y, z))
 
 # Doesn't work because y and z have different number of elements
 df2 <- tribble(
@@ -549,7 +549,7 @@ df2 <- tribble(
    2, c("b", "c"),   3
 )
 df2
-df2 %>% unnest(y, z)
+df2 %>% unnest(c(y, z))
 ```
 
 The same principle applies when unnesting list-columns of data frames. You can unnest multiple list-cols as long as all the data frames in each row have the same number of rows.