groupby 在 R 中的类字符列上进行汇总

Question

我有一个包含 A 列和 B 列的数据框，其中 B 是我想按 A 列分组的字符串，并将 B 的元素组合成一个字符串，然后我可以在其中获取该分组字符的唯一元素（使用 R 4.0.5 和dplyr )。

例子：

df <- data.frame(a = c("a","a","a","b","b","b"), c = c("d","d","d","d","e","e"))

df.new <- df %>%
             group_by(a) %>%
             summarise(new_strs = c(c)) 

输出这个data.frame ：

1 a     d       
2 a     d       
3 a     d       
4 b     d       
5 b     e       
6 b     e    

所需的 DF 输出：

1 a     c("d","d","d")             
6 b     c("d","e","e")    

如何更改代码以获得结果。 我也尝试过paste(x, collapse = ",")但它给出了一个字符串而不是一组字符串。

Answer 1

我的第一个想法是使用list而不是c

exampledf <- data.frame(a = c("a","a","a","b","b","b"), c = c("d","d","d","d","e","e"))

exampledf %>%
  group_by(a) %>%
  summarise(new_strs = list(c))

Answer 2

我们可以使用来自base R aggregate

aggregate(c ~ a, df, list)
  a       c
1 a d, d, d
2 b d, e, e