r - 寻找最频繁的组合

Question

我有一个包含 2 列、ID 号和品牌的数据框:

X1     X2
1234   A89
1234   A87
1234   A87
1234   A32
1234   A27
1234   A27
1235   A12
1235   A14
1235   A14
1236   A32
1236   A32
1236   A27
1236   A12
1236   A12
1236   A14
1236   A89
1236   A87
1237   A99
1237   A98

我想找到就 ID 号而言最常出现的前 3 个品牌组合:

A89, A87
A32, A27
A12, A14

我试过:
图书馆(dplyr)

 df %>% 
  group_by(X1,X2) %>%
  mutate(n = n()) %>%
  group_by(X1) %>%
  slice(which.max(n)) %>%
  select(-n)

但它不能正常工作。我将不胜感激任何想法或想法!

Answer 1

这是在基础 R 中实现的方法。我们拆分 X2来自 X1然后为每个子组获取两个值的组合。然后我们捕获三个最常见的。

with(data.frame(table(unlist(lapply(split(df$X2, df$X1), function(x)
    combn(unique(x), min(2, length(x)), paste, collapse = "-"))))),
    as.character(Var1[head(order(Freq, decreasing = TRUE), 3)]))
#[1] "A12-A14" "A32-A27" "A89-A87"

数据

df = structure(list(X1 = c(1234L, 1234L, 1234L, 1234L, 1234L, 1234L, 
1235L, 1235L, 1235L, 1236L, 1236L, 1236L, 1236L, 1236L, 1236L, 
1236L, 1236L, 1237L, 1237L), X2 = c("A89", "A87", "A87", "A32", 
"A27", "A27", "A12", "A14", "A14", "A32", "A32", "A27", "A12", 
"A12", "A14", "A89", "A87", "A99", "A98")), .Names = c("X1", 
"X2"), class = "data.frame", row.names = c(NA, -19L))