如何在R中聚合无向组合[重复]

Question

我有一个 3 列的数据框

A B 1
A B 1
A C 1
B A 1

我想对其进行聚合，使其认为 A-B 和 B-A 的组合相同，从而得到 ​​p>

A B 3
A C 1

我该怎么做？

Answer 1

在前两列使用pmin 和pmax，然后按计数分组：

library(dplyr);
df %>% group_by(G1 = pmin(V1, V2), G2 = pmax(V1, V2)) %>% summarise(Count = sum(V3))
Source: local data frame [2 x 3]
Groups: G1 [?]

     G1    G2 Count
  (chr) (chr) (int)
1     A     B     3
2     A     C     1

对应的data.table 解决方案是：

library(data.table)
setDT(df)
df[, .(Count = sum(V3)), .(G1 = pmin(V1, V2), G2 = pmax(V1, V2))]

   G1 G2 Count
1:  A  B     3
2:  A  C     1

数据：

structure(list(V1 = c("A", "A", "A", "B"), V2 = c("B", "B", "C", 
"A"), V3 = c(1L, 1L, 1L, 1L)), .Names = c("V1", "V2", "V3"), row.names = c(NA, 
-4L), class = "data.frame")