r - 用数字将相似的字符串分组并保持首次出现的顺序

Question

我有一个数据框，看起来像这个例子(只是大得多):

var <- c('Peter','Ben','Mary','Peter.1','Ben.1','Mary.1','Peter.2','Ben.2','Mary.2')
v1 <- c(0.4, 0.6, 0.7, 0.3, 0.9, 0.2, 0.4, 0.6, 0.7)
v2 <- c(0.5, 0.4, 0.2, 0.5, 0.4, 0.2, 0.1, 0.4, 0.2)
df <- data.frame(var, v1, v2)

      var  v1  v2
1   Peter 0.4 0.5
2     Ben 0.6 0.4
3    Mary 0.7 0.2
4 Peter.1 0.3 0.5
5   Ben.1 0.9 0.4
6  Mary.1 0.2 0.2
7 Peter.2 0.4 0.1
8   Ben.2 0.6 0.4
9  Mary.2 0.7 0.2

我想根据不带后缀的名称对 'var' 中的字符串进行分组，并保留首次出现的原始顺序。期望的输出:

      var  v1  v2
1 Peter   0.4 0.5 # Peter appears first in the original data
2 Peter.1 0.3 0.5
3 Peter.2 0.4 0.1
4     Ben 0.6 0.4 # Ben appears second in the original data
5   Ben.1 0.9 0.4
6   Ben.2 0.6 0.4
7    Mary 0.7 0.2 # Mary appears third in the original data
8  Mary.1 0.2 0.2
9  Mary.2 0.7 0.2

我怎样才能实现这一目标？

谢谢!

Answer 1

带有 sub 和 data.table::chgroup 的紧凑选项

df[chgroup(sub("\\..", "", df$var)),]

      var  v1  v2
1   Peter 0.4 0.5
4 Peter.1 0.3 0.5
7 Peter.2 0.4 0.1
2     Ben 0.6 0.4
5   Ben.1 0.9 0.4
8   Ben.2 0.6 0.4
3    Mary 0.7 0.2
6  Mary.1 0.2 0.2
9  Mary.2 0.7 0.2

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chgroup groups together duplicated values but retains the group order (according the first appearance order of each group), efficiently