在dplyr链中使用table() [英] Using table() in dplyr chain

问题描述

有人可以解释为什么table()在dplyr-magrittr管道操作链中不起作用吗?这是一个简单的说明:

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)

sort.list(y)中的错误:"x."对于"sort.list"必须是原子的 您是否在清单上称呼排序"?

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

但这当然有效:

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

推荐答案

此行为是设计使然:由于您自己没有.，因此仍将小标题作为第一个参数传递，因此它实际上更像是

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)

magrittr的官方解决方法是使用花括号

The official magrittr work-around is to use curly braces

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

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