r - 组织子组字符串(文本)

Question

我正在尝试转换类似这样的 df 格式:

df <- data.frame(first = c("a", "a", "b", "b", "b", "c"), 
  words =c("about", "among", "blue", "but", "both", "cat"))

df
  first words
1     a about
2     a among
3     b  blue
4     b   but
5     b  both
6     c   cat

转换成如下格式:

df1
  first           words
1     a    about, among
2     b blue, but, both
3     c             cat
> 

我试过了

aggregate(words ~ first, data = df, FUN = list)

  first   words
1     a    1, 2
2     b 3, 5, 4
3     c       6

和tidyverse:

df %>%
  group_by(first) %>% 
  group_rows()

如有任何建议，我们将不胜感激!

Answer 1

一个data.table解决方案:

library(data.table)

df <- data.frame(first = c("a", "a", "b", "b", "b", "c"), 
  words =c("about", "among", "blue", "but", "both", "cat"))

df <- setDT(df)[, lapply(.SD, toString), by = first]

df
#    first           words
# 1:     a    about, among
# 2:     b blue, but, both
# 3:     c             cat

# convert back to a data.frame if you want
setDF(df)