在R语言中按分组将字符串合并为单个字符串的实现

输入数据 #

library(dplyr)  

Input <- tibble(
      UID = c("Code001", "Code001","Code002","Code002","Code002","Code002","Code003","Code003","Code003","Code004","Code005","Code005"),
      Name = c("NameABC", "Name JHB", "NameYDB", "Name & KBC","Name-S-D-T", "Name DF-R","NameMEY", "Name PeU","Name Eed", "NameBOR", "Name-Ptg","NameLKD")) 

需求说明 #

针对每个唯一的UID，将对应的Name值合并为单个字符串，规则如下：

• 仅1个Name值：直接保留该值
• 2个Name值：用&分隔
• 超过2个Name值：前序值用逗号分隔，最后两个值用&分隔

期望输出 #

Output <- tibble(
      UID = c("Code001", "Code002","Code003","Code004","Code005"),
      Name = c("NameABC & Name JHB", "NameYDB, Name & KBC, Name-S-D-T & Name DF-R", "NameMEY, Name PeU & Name Eed", "NameBOR", "Name-Ptg & NameLKD")) 

解决方案代码 #

使用dplyr分组处理即可实现需求：

library(dplyr)

Input %>%
  group_by(UID) %>%
  summarise(Name = {
    n <- n()
    case_when(
      n == 1 ~ first(Name),
      n == 2 ~ paste(Name, collapse = " & "),
      n > 2 ~ paste(c(paste(Name[1:(n-2)], collapse = ", "), paste(Name[(n-1):n], collapse = " & ")), collapse = ", ")
    )
  }, .groups = "drop")

代码逻辑说明 #

1. group_by(UID)：按UID对数据分组
2. 分组内处理逻辑：
   • 用n()获取当前组的Name数量
   • 通过case_when分支判断：
     • 数量为1时，直接取组内唯一的Name值
     • 数量为2时，用paste加&合并两个值
     • 数量大于2时，先合并前n-2个值为逗号分隔的字符串，再合并最后两个值为&分隔的字符串，最后将这两部分用逗号连接
3. .groups = "drop"：取消分组，返回标准的tibble结构

内容的提问来源于stack exchange，提问作者Chris