r将列表列转换为字符向量，其中列表是字符

Question

我正在尝试将列表转换为单个字符值，或者基本上是从此开始：

test <- data.frame(a = c(1,1,1,2,2,2), b = c("a", "b", "c", "d", "e", "f" )) %>% 
  group_by(a) %>% summarise(b = list(b))

对此：

test <- data.frame(a = c(1,2), b = c("a, b, c", "d, e, f" )) 

Answer 1

干得好：

test %>% 
  mutate(b = sapply(b, toString))

## A tibble: 2 x 2
#      a b      
#  <dbl> <chr>  
#1    1. a, b, c
#2    2. d, e, f