RobertMc RobertMc -4 years ago 78
R Question

Using table() in dplyr chain

Can someone explain why

table()
doesn't work inside a chain of dplyr-magrittr piped operations? Here's a simple reprex:

tibble(
type = c("Fast", "Slow", "Fast", "Fast", "Slow"),
colour = c("Blue", "Blue", "Red", "Red", "Red")
) %>% table(.$type, .$colour)



Error in sort.list(y) : 'x' must be atomic for 'sort.list'
Have you called 'sort' on a list?


But this works of course:

df <- tibble(
type = c("Fast", "Slow", "Fast", "Fast", "Slow"),
colour = c("Blue", "Blue", "Red", "Red", "Red")
)

table(df$type, df$colour)


Blue Red
Fast 1 2
Slow 1 1

Answer Source

This behavior is by design: https://github.com/tidyverse/magrittr/blob/00a1fe3305a4914d7c9714fba78fd5f03f70f51e/README.md#re-using-the-placeholder-for-attributes

Since you don't have a . on it's own, the tibble is still being passed as the first parameter so it's really more like

... %>% table(., .$type, .$colour)

The official magrittr work-around is to use curly braces

... %>% {table(.$type, .$colour)}
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