如何在包含变量的字符串中添加自定义字符取决于组变量？
下面是虚拟输入数据集：

library(tidyverse)
unit <- c(50, 50, 40, 40, 30, 30, 20, 20, 10, 10)

id <- c("A100", "A101", "A102", "A103", "A100", "A101", "A102", "A103", "A101", "A100")
variation <- c("aaa1", "aaa1", "bbb1", "aaa2", "b1","a3", "a1", "b1", "a1", "b1" )
result <- c("Way1", "Way1", "Way2", "Way2", "Way3","Way1", "Way2", "Way3", "Way4", "Way1" )

data <- data.frame(id, variation, result, unit)
head(data)

#      id variation result unit
# 1  A100      aaa1   Way1   50
# 2  A101      aaa1   Way1   50
# 3  A102      bbb1   Way2   40
# 4  A103      aaa2   Way2   40
# 5  A100        b1   Way3   30
# 6  A101        a3   Way1   30
# 7  A102        a1   Way2   20
# 8  A103        b1   Way3   20
# 9  A101        a1   Way4   10
# 10 A100        b1   Way1   10

是否可以在“变量”列中添加自定义字符串字符取决于“单位”列？
下面是预期的输出：

#         id variation result unit
# 1  A100      A1.aaa1   Way1   50
# 2  A101      A1.aaa1   Way1   50
# 3  A102      A2.bbb1   Way2   40
# 4  A103      A2.aaa2   Way2   40
# 5  A100        A3.b1   Way3   30
# 6  A101        A3.a3   Way1   30
# 7  A102        A4.a1   Way2   20
# 8  A103        A4.b1   Way3   20
# 9  A101        A5.a1   Way4   10
# 10 A100        A5.b1   Way1   10

正如你所看到的，如果“unit”变量是相同的，那么相同的自定义字符串被添加到“variation”变量。
优选dplyr和base R函数。